Internal branding: conceptualization from a literature review and opportunities for future research

Recently, internal branding has gained relevance in the marketing literature because researchers recognize that corporate brand management not only implicates external actions but also an internal approach that involves employees. Despite the growing interest, there is no consensus among authors about antecedents, dimensions, and outcomes of internal branding. In this sense, this paper aims to explore the conceptualization of internal branding and to offer opportunities for future research. The study is a systematic literature review that uses a specific database. The contributions of each article were extracted, organized, and processed following systematic procedures. This review defines internal branding as a cross-functional process that involves both marketing and human resource departments. It focuses on managing the brand internally through brand-centered human resource management, internal brand communications, and brand leadership, with the aim of achieving brand outcomes among employees (brand understanding, brand identification, brand commitment, brand loyalty, brand citizenship behaviors) so they can build brand equity in front of external stakeholders. Although a lack of consensus had been established, the literature evidenced similarities that gave rise to the conceptualization proposed in this study. Nevertheless, the discussion about internal branding is still open because there are several issues to investigate in this field.


Introduction
In the business context of the twenty-first century, human resources can represent a source of competitive advantage for organizations. Several authors King 2010;Poulis and Wisker 2016;Ragheb et al. 2018) highlight the importance of employees to generate differentiation in an increasingly competitive environment. The importance of employees for organizational success was recognized more than 40 years ago when Berry highlighted the need to see employees as internal customers (Du Preez and Bendixen 2015). Nowadays, employees are considered key actors within organizations who contribute to achieving corporate objectives and, in turn, to build brand equity (Punjaisri and Wilson 2011).
Employees are the visible face of the organization, especially in service companies Schlager et al. 2011). Therefore, their behaviors largely determine brand experience for customers (Erkmen and Hancer 2015;Karanges et al. 2018). It has been recognized that interactions between employees and customers impact customer satisfaction, customer loyalty, and finally, corporate brand equity (Saleem and Iglesias 2016). In this sense, brand management can not only focus on external stakeholders, but also an internal orientation to make employees brand promoters through their actions (Anisimova and Mavondo 2010). In other words, an effective corporate brand management must balance both external and internal efforts (Aydon 2009;Foster et al. 2010;Hytti et al. 2015;Kang 2016).
From this internal orientation of brand management emerges the concept of internal branding, which is defined as "a management tool for ensuring that employees have a Electronic supplementary material The online version of this article (https ://doi.org/10.1057/s4126 2-020-00219 -1) contains supplementary material, which is available to authorized users. shared understanding of the desired corporate brand and that they are able and willing to reflect this image to other stakeholders through their behavior" (Ragheb et al. 2018, p.83). Internal branding provides to employees a clear direction to effectively deliver the meaning and values of the brand to external customers (Dechawatanapaisal 2018;Sandbacka et al. 2013).
Despite the growing relevance of this new approach in brand management, traditionally external branding has received greater interest from researchers and managers (Devasagayam et al. 2010;Hytti et al. 2015;Kang 2016;Wagner and Peters 2009). For this reason, some authors (Punjaisri and Wilson 2011;Punjaisri et al. 2009a;Saleem and Iglesias 2016) call for further investigation about internal branding because there are some inconsistencies about its conceptualization and its implementation process. There is no consensus among researchers about the definition of internal branding (Du Preez and Bendixen 2015), and sometimes it is used interchangeably with related concepts such as employer branding (King and Grace 2010;Saini and Jawahar 2019) or internal marketing Bailey et al. 2016). As Saleem and Iglesias (2016) said: "to date no single definition of internal branding has been accepted, much less so a conclusive view as to what makes internal branding success" (p. 46). Thus, internal branding is still considered as a developing subject that needs more theoretical and empirical studies (King and Grace 2010;Piehler et al. 2018;Saleem and Iglesias 2016).
Based on the above statements, this article aims to explore the conceptualization of internal branding to offer a conceptual framework. It also seeks to identify opportunities for future research in this field. First, this literature review presents the conceptualization of internal branding through its antecedents, dimensions, and outcomes. Also, the study proposes a conceptual model that summarizes the conceptualization of internal branding. Then, some managerial implications are presented, and the last section reveals some guidelines for future research.

Method
The current study is a systematic literature review. It is defined as a process that uses a structured approach to select and analyze the literature published about a particular subject (Gregory and Denniss 2018). The main characteristic of this research design is that it uses a rigorous and critical process to review the literature, making it easier to understand (Saleem and Iglesias 2016).
The process of finding documents about internal branding was effectuated in the Emerald Insight database, considering articles published during the last 10 years (2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019). Three search equations were used to find the documents that would be included in this review. The first search considered the articles that contained the term "internal branding" in their title or abstract: (content-type:article) AND (title:"internal branding" OR (abstract:"internal branding")). This first search showed a result of 57 articles. The second search considered the articles that simultaneously included the terms "internal branding" and "internal marketing" due to some authors Iyer et al. 2018;Ragheb et al. 2018;Sharma and Kamalanabhan 2012) establish a strong relationship between these both concepts. The search equation "(content-type:article) AND ("internal branding" AND ("internal marketing"))" showed a result of 118 documents. The third search considered the articles that integrated the terms "internal branding" and "human resource management" because several authors (Anselmsson et al. 2016;Bodkin et al. 2016;Chang et al. 2016;Dechawatanapaisal 2018;Foster et al. 2010;Hofer and Grohs 2018;Iglesias and Saleem 2015;Iyer et al. 2018;Kang 2016;Punjaisri and Wilson 2011;Saleem and Iglesias 2016;Uen et al. 2012) recognize the importance of the human resource department for the internal branding process. This last search equation "(content-type:article) AND ("internal branding" AND ("human resource management"))" showed a result of 164 articles.
The results of each search were organized in three lists (IB, IB and IM, IB and HRM), identifying the following information of each article: year of the publication, title, authors, journal, category or quartile of the journal (based on Scimago ranking https ://www.scima gojr.com/), and abstract. These lists showed a general panorama of the initial sample (339 results), but then some inclusion and exclusion criteria were applied to consider the most relevant information. Firstly, it was established that all documents included in this review must belong to journals rank in quartile Q1 or Q2 due to these quartiles contain the most prestigious journals. This criteria excluded eight documents from the first list (IB), 21 documents from the second one (IB and IM), and 36 documents from the third one (IB and HRM). Also, this phase excluded one result in the first list (IB) and two results in the second one (IB and IM) which were editorial records. The next step was to read the abstracts to identify the relevance of each paper for the aim of this study. This process excluded those articles that were not directly related to the central issue of this study: three documents were excluded from the first list (IB), 42 documents were excluded from the second one (IB and IM), and 56 documents were excluded from the third one (IB and HRM). After applying all the inclusion and exclusion criteria, the final sample for each list was: 46 documents for the first list (IB), 55 documents for the second one (IB and IM), and 70 documents for the third one (IB and HRM). By integrating the final result of the three lists, a sample of 171 documents was obtained. However, many articles appeared simultaneously in the three lists so that, when the information was consolidated, a final list of 76 documents was obtained.
The sample was complemented by the inclusion of six articles from the special issue of the Journal of Brand Management dedicated to Internal Brand Management. This special issue was included as an independent search because it represents a relevant contribution to the theory of internal branding. The inclusion of these articles determined a definitive sample of 82 documents, which were the basis for developing this systematic literature review.
Then, this study used a matrix in Microsoft Excel to organize the contributions extracted from each document. The information extracted from each paper was the following: year of publication, title, authors, methodology, contributions of the document to the conceptualization of internal branding, and opportunities for future research according to authors. It is important to note that the contributions from each paper were extracted considering different categories, such as contributions to the definition, antecedents, dimensions, and outcomes of internal branding. This process facilitated the treatment and interpretation of the information.

An initial approach to internal branding
Before developing the conceptualization of internal branding, it is necessary to understand some key ideas. Branding or brand management is the process of administering and promoting the brand through strategic marketing efforts in order to achieve economic exchanges and expected benefits (Aydon 2009). The use of brands dates back to 1500 BC when greeks marked their cattle to differentiate it from the rest. However, the first corporate brand initiatives date back in 1931, promoted by Procter and Gamble, which started using labels on their products to help consumers identify them. After the Second World War, Ford and General Motors got involved in advertising battles, which nowadays occur in all industries as a way to educate people about the distinctive qualities of their products and services (Whisman 2009).
In 1960 the American Marketing Association defined the brand as the name, term, sign, symbol, or a combination of them, used to identify or differentiate goods and/or services from competitors (Skaalsvik and Olsen 2014); however, this definition has evolved and now a brand involves multiple emotional dimensions that impregnate qualities and characteristics distinctive that are assimilated by the consumers (Hytti et al. 2015;Sheikh and Lim 2015). A brand should not be considered only as a name, term, design, or symbol, but is also an intangible resource that builds value for companies . Currently, a brand is defined as the global promise or proposition that a firm projects in comparison with the experience that the brand delivers. (Aydon 2009).
The brand is a strategic resource that can become a distinctive sign of consistency and quality (Erkmen and Hancer 2015). Because of this, firms have focused their efforts on building strong brands through brand management; however, traditionally brand initiatives have focused on external stakeholders, but recently, the importance of internal customers is recognized and also the need to promote the brand internally (Devasagayam et al. 2010;Kang 2016;Sheikh and Lim 2015). King and Grace (2012) state that employees are particularly important in brand management because they deliver the functional and emotional values of the brand through their interactions with customers. Employees are essential for delivering the brand promise; therefore, they strongly influence on what customers perceive about the organization and the brand (Aydon 2009;Cheung et al. 2014;Du Preez and Bendixen 2019;Zhang et al. 2016). Employees are considered as the service brand because they play a key role in the personification of corporate identity and the building of brand reputation through their behaviors Helm et al. 2016;Ragheb et al. 2018). If employees do not understand the brand, they will not be able to deliver the brand promise promulgated to customers through external branding actions (Erkmen and Hancer 2015). The messages transmitted to employees about the brand are as important as those sent to external customers (Anisimova and Mavondo 2010;Pinar et al. 2016). When employees internalize the meanings and values of the brand, they will be able to deliver it to external customers .
Based on the above context, internal branding emerges in the marketing literature to promote the brand internally to guarantee that employees properly deliver the brand promise to external stakeholders (Foster et al. 2010). Employees need to understand clearly the brand promise so that they can deliver it (Dechawatanapaisal 2018;Murillo and King 2019a). Thus, through internal brand management, employees can acquire the skills and knowledge required to represent the Brand (King and Grace 2010). When internal branding efforts are implemented, employees can understand the brand and, as a consequence, they develop attitudes in favor of it (Anisimova and Mavondo 2010).
There is debate over the exact date internal branding first appears in marketing literature. Du Preez and Bendixen (2015) established that this concept appeared in the 70s when the approach of internal marketing suggested seeing employees as internal customers. According to Ragheb et al. (2018), during the 80s and 90s, companies began using brand management practices, including strategies oriented to employees, but they clarify that internal branding acquires relevance in the late 90's. On the other hand, Schmidt and Baumgarth (2018) assured that this term was used for the first time in 1999. Finally, Bodkin et al. (2016) affirm that several articles were published in the middle of the 2000s focusing on explaining internal branding and the reasons why managers should implement this process in their companies.
Although there is no consensus about the beginnings of internal branding, this topic has gained greater interest among academics and professionals in recent years, generating multiple research in various industries. However, some authors (Hytti et al. 2015;King and Grace 2010;Piehler et al. 2018;Saleem and Iglesias 2016;Zhang, et al. 2016) recognize that internal branding is a developing subject, which needs more empirical and conceptual studies to strengthen its theory.

Conceptualization of internal branding
Internal branding has emerged in the marketing literature as a strategy to promote the brand within the organization to ensure that employees adequately deliver the brand promise to external customers Sang and Swinney 2012). Internal branding is considered a subset of internal marketing due to its focus on the internal customer Iyer et al. 2018;Ragheb et al. 2018;Sharma and Kamalanabhan 2012). Hofer and Grohs (2018) affirm that internal marketing and internal branding look similar because both concepts seek to positively influence the beliefs, attitudes, and behaviors of employees toward the firm. Mohammad 2011) establish that internal marketing represents the general vision of internal orientation. Its objective is to create value for internal customers (employees), so that they get motivated, trained, and committed to deliver an excellent service and to achieve marketing objectives. Internal branding focuses on a specific aspect of marketing, i.e., brand management among employees to build powerful brands to external customers Ragheb et al. 2018). Thus, although internal marketing and internal branding are two closely related concepts, there are differences regarding the precision of their objectives. These aspects must be considered to avoid the indiscriminate use of both terms. Instead, internal marketing should be considered as a facilitator of internal branding (Vella et al. 2009).
Employer branding is another concept that has been confused with internal branding due to its orientation toward employees (Foster et al. 2010;Schlager et al. 2011). However, Saleem and Iglesias (2016) clarify that both terms should not be used interchangeably because employer branding aims to make the firm an attractive place to work for potential employees, while internal branding focuses on promoting the brand among current employees to motivate them to successfully deliver the brand to external stakeholders. But it is necessary to recognize that both concepts are related because Hoppe (2018) empirically demonstrated that internal branding is an antecedent of employer branding. Some researchers (Du Preez and Bendixen 2015;Punjaisri and Wilson 2011;Saleem and Iglesias 2016) agree that the confusion about internal branding is since there is no unified definition. However, over time a significant number of definitions have been generated, which opens up the possibility of formulating a unified definition. Table 1 shows some of the most relevant definitions identified in this review.
In the previous definitions, it is possible to identify different perspectives about internal branding; however, there are some common aspects among authors. Firstly, it is clear that internal branding consists of an internal orientation of the brand, centered on employees. It seeks to promote the brand among employees so that they exhibit positive attitudes and behaviors to the brand. The definitions highlight the importance of employees in brand performance, even they are invited to become brand ambassadors Quaratino and Mazzei 2018;Schmidt and Baumgarth 2018). For this reason, internal branding focuses on aligning employees with brand values to create a workforce committed to deliver what the brand promises. Secondly, it is possible to identify that although internal branding is focused within the organization (employees), its ultimate purpose is to generate a positive impact on the brand externally. Most of the definitions evidence that internal branding seeks to ensure that employees correctly deliver the brand promise to external customers. It attempts that attitudes and behaviors of employees are consistent with brand values and, in consequence, customers perceive a positive brand experience during the service. And, thirdly, the definitions show that one of the main objectives of internal branding is to create synergy between external and internal brand messages. Some authors (Anisimova and Mavondo 2010;Dechawatanapaisal 2018;Helm et al. 2016;Pinar et al. 2016;Punjaisri et al. 2009b) recommend maintaining consistency between internal and external brand messages. Therefore, it is necessary to align the employee behaviors to brand values to make them correctly deliver the brand promise.
Thus, the initial discussion defines internal branding as an internal orientation of brand management and its objective is to promote the brand internally to ensure that employees are willing to deliver the brand promise to external stakeholders, creating consistency between internal and external brand messages.  Punjaisri et al. (2009b) Internal branding aims at inducing employees' behavioral changes to support the delivery of the brand promise Ghose (2009) Internal branding consists of motivation level of the employees to serve the brand vision along with resource support by the organization to ensure the brand vision Whisman (2009) Internal branding is a formal program of engaging internal constituents in a dialogue about the brand development process Foster et al. (2010) Internal branding focuses largely on the adoption of the branding concept inside an organization to ensure that employees deliver the brand promise to the external stakeholders Punjaisri and Wilson (2011) Internal branding is about ensuring that the brand promise will be transformed by employees into reality, reflecting the espoused brand values that set customers' expectations King and Grace (2012) Internal brand management seeks to internalize the brand so that employees are better equipped to fulfill the explicit and implicit promises inherent in the brand Chang et al. (2012) Internal branding is regarded as the process of promoting the brand to employees, educating them what the brand value is, and then making employees' perception and behaviors transformed. During the process, if the employees' needs are satisfied through the exchange relations, the employees can result in better brand attitude, brand psychological ownership and altruistic behavior, thus contribute to customer satisfaction Sharma and Kamalanabhan (2012) Internal branding is a result of employer's internal communication effort to develop a workforce that is committed, loyal and identifies with the set of organizational values and goals Sang and Swinney (2012) Internal branding is defined as aligning employees' disparate attitudes and beliefs toward an organization's brand value to earn commitment (employee buy-in) toward the organization. The main purpose of internal branding is to ensure all employees of an organization have congruent attitudes toward the brand values and are committed to delivering these values to customers Cheung et al. (2014) Internal branding is about ensuring that employees transform the brand promise into reality, which helps to meet customers' expectations through the espoused brand values. It is a means to create a powerful corporate brand, and is an enabler of an organization's success by delivering the brand promise to meet customers' brand expectations Du Preez and Bendixen (2015) Internal brand management strives to deliver staff who are "living the brand" values, delivering an on-brand experience; resulting in customers being well served. This process focuses on the internal development, strengthening and maintenance of a firm's brand Saleem and Iglesias (2016) Internal branding is a process through which brands aim to facilitate the internalization of brand values by employees, so that employee behavior aligns with these brand values when delivering the brand promise Pinar et al. (2016) Internal branding involves training service delivery personnel on the brand promise and brand strategy in order for them to provide customers with the desired brand experience (enabling the brand promise). Bodkin et al. (2016) Internal branding consists of marketing directed toward internal employees to make them brand ambassadors, developing attitudes and behaviors in favor of the brand Du Preez et al. (2017) Internal branding activities seek to promote the brand for the purpose of ensuring that its internal stakeholders (i.e., employees) accept the value that the brand represents and transform it into reality when serving customers Ragheb et al. (2018) Internal branding is considered a tool for ensuring that employees have a shared understanding of the desired corporate brand image and that they are able and willing to reflect this image to other stakeholders through their own behavior Dechawatanapaisal (2018) Internal branding involves activities that help employees comprehend and buy into brand values, and facilitate them to perform the roles as advocated by the management with a goal of keeping consistency between internal and external brand message Anees-ur-Rehman et al. (2018) Internal branding can be used as an important tool to align firm's brand values with those of employees Hoppe (2018) Internal branding efforts aim to strengthen the corporate brand, e.g., by facilitating brand-supportive behaviors from employees Hasni et al. (2018) Internal branding empowers a company to fulfill its brand promise to its consumers through employees Iyer et al. (2018) Internal branding is an extension of the internal marketing approach that focuses on developing symbolic ties between employees and brands. Involves developing the human capital through training, seminars, and communication for brand management

Antecedents of internal branding
The antecedents of internal branding have not been discussed extensively in the literature. Most of the research about internal branding has focused on studying its components and outcomes, but it is also necessary to analyze what factors facilitate the implementation of internal branding. This review identified that brand orientation and internal market orientation (IMO) are two crucial organizational antecedents for internal branding because they both create favorable conditions for its implementation process. Brand orientation is defined by Urde (1994) as "an approach in which the processes of the organization revolve around the creation, development and protection of brand identity in an ongoing interaction with target customers with the aim of achieving lasting competitive advantages in the form of brands" (cited by Zhang et al. 2016, p.85). In other words, brand orientation is the degree to which a firm catalog the brand and brand management as a critical factor to their success. Brand-oriented organizations do not only expect to fulfill customer needs but also to build a strategic meaning to their brands ). If an organization is a brand-oriented firm, its managers will be willing to contribute efforts and resources to promote the brand internally because they recognize the positive implications in the long term ). Thus, it will be easier to implement internal branding in brand-oriented organizations than those that are not.
On the other hand, internal market orientation (IMO) was also identified as a key antecedent of internal branding because it improves perceptions of employees about the brand . IMO represents the multidimensional version of internal marketing. It is defined as management behaviors that lead firms to create value for employees through the identification and satisfaction of their needs, motivating them to support the marketing objectives Liu et al. 2019). Organizations that adopt IMO consider their employees as fundamental actors to business success, thus they attempt to create value to employees through different strategies (Boukis and Gounaris 2014). In this sense, IMO is shown as a facilitator of internal branding because internal orientation motivates managers to execute strategies for employees ).
On the other hand, the literature review leads to identify that internal branding is a cross-functional process that involves simultaneous efforts from marketing and human resources departments (Anselmsson et al. 2016;Bodkin et al. 2016;Dechawatanapaisal 2018;Foster et al. 2010;Hofer and Grohs 2018;Iglesias and Saleem 2015;Iyer et al. 2018;Kang 2016;Punjaisri and Wilson 2011;Saleem and Iglesias 2016;Uen et al. 2012). The cross-functional effort between these two departments is not an antecedent of internal branding, but in practical terms, it is a necessary condition for the implementation process. The marketing department manages symbolic and experimental aspects of the brand, communication about the brand values, and all the experiences that employees live with the brand . The human resources department is responsible for recruit employees according to brand values, training about the brand, and motivate employees to deliver the brand promise (Anselmsson et al. 2016). In this sense, the barriers between marketing and human resource management must be shot down to create new roles and mutually design brand experiences for employees (Dechawatanapaisal 2018). This process implies avoiding the old paradigm that internal branding is the sole responsibility of the marketing area, in terms of internal communications ), since some processes and structures of internal branding fall within the domain of human resource management.

Dimensions of internal branding
Just as the definition of internal branding has not been clearly defined, its dimensions also need to be clarified. During this review, different components were identified according to authors. For example, Punjaisri et al. (2009a, b) state that internal branding involves internal communication from the marketing department to share information about the brand and training programs from the human resource department to improve employee brand knowledge. In the same vein, others authors Gammoh et al. 2018;Hofer and Grohs 2018;Iyer et al. 2018;Zhang et al. 2016) express that internal communication and training programs are the main dimensions of internal branding. On the other hand, Xie et al. (2016) ensure that job participation is an important component to promote the brand among employees through effective communication between leaders and employees that facilitates the appropriation of brand values within firms. The authors also highlight the role of leaders in internal brand management due to they are responsible for motivating employees to acquire behaviors aligned with brand values.
A significant contribution to this issue was made by Saleem and Iglesias (2016), who identified five dimensions of internal branding in their literature review: (1) brand ideologies that refer to incorporate the mission, vision, objectives, norms, and values into the corporate brand promise; (2) brand leadership that involves the efforts of leaders and employees to dissemination brand ideologies; (3) brandcentered human resource management consisting of recruiting, selecting, compensating and training employees using structures that promote brand values; (4) internal brand communication to communicate the brand message within the organization; and (5) internal brand communities which are physical or virtual communities that encourage brand identification among employees.
The above discussion reveals that there is no consensus about the dimensions of internal branding. For this reason, it is necessary to identify the main components according to the literature. Table 2 shows the dimensions identified in this review.
The information presented in Table 2 determines that internal brand communications, branding training programs, brand-oriented recruitment, brand rewards systems, brand leadership, and brand-based performance evaluation are the most important dimensions of internal branding. Within these dimensions, the recruitment, training, and compensation activities are functions from the human resources department; therefore, they could be integrated into the main dimension named brand-centered human resource management, which was cited by several authors Chiang et al. 2018;Du Preez et al. 2017;Foster et al. 2010;Helm et al. 2016;King and Grace 2010;Piehler et al. 2016;Saleem and Iglesias 2016). Thus, the main dimensions of internal branding proposed in this research are the follows: brandcentered human resources management (brand-oriented recruitment, branding training programs, brand rewards systems, and brand-based performance evaluation), internal brand communications, and brand leadership.
Other dimensions identified in the literature, such as internal brand communities, brand ideologies, brand ambassador programs, brand promotional products, and sponsorship, need further empirical studies to be considered principal dimensions of internal branding. External brand communications were identified in the literature review for their influence on what employees perceive about the brand (Hofer and Grohs 2018). However, these actions should not be considered as a dimension of internal branding because their target audience is not employees, but external stakeholders. Based on Saleem and Iglesias (2016), external brand communications  Hofer and Grohs (2018) should be considered as a support within internal brand communications. During the review, it was possible to identify other components, but they could be included within the dimensions already identified. For example, Hasni et al. (2018) and King (2010) identified role clarity as a dimension of internal branding. They define it as the clarity that employees have about their functions thanks to brand knowledge; however, role clarity could be distinguished as a result of branding training programs because this dimension aims to improve brand knowledge and abilities that employees need to develop their functions according to their roles and brand values Cheung et al. 2014;Gammoh et al. 2018).
Organizational socialization and positive relationship orientation were other components identified by King and Grace (2012). Organizational socialization implies supporting employees to acquire the skills, knowledge, and understanding necessary to fulfill their duties and responsibilities, but these actions could be included within branding training programs and internal brand communications because both seek the same consequences (Dechawatanapaisal 2018;Zhang et al. 2016). On the other hand, positive relationship orientation is defined as the positive behaviors that employees receive from the organization (respect, cooperation, communication, trust), establishing a reciprocal relationship between both, however, Punjaisri and Wilson (2011) ensure that these elements are part of the work environment that influence employee brand behaviors, but they are not a dimension of internal branding.
To conclude the analysis of the dimensions of internal branding, the following paragraph to describe the main dimensions identified in this literature review (brand-centered human resources management, internal brand communications, and brand leadership).

Brand-centered human resources management
The human resources department becomes a key actor within the internal branding process Chiang et al. 2018;. Human resources management impacts on how employees interact with customers, which in turn influences their perceptions about the Brand (Anselmsson et al. 2016;App and Büttgen 2016;Chang et al. 2016;Vella et al. 2009). The reason is that "many processes and structures that fall under the domain of human resources management are essential in aligning employee behavior with brand values" (Saleem and Iglesias 2016, p.49).
In the context of internal branding, recruitment, training, rewards, and evaluation processes are considered crucial to align employees with brand values (Anselmsson et al. 2016;Chiang et al. 2018;Devasagayam et al. 2010;Du Preez et al. 2017;Piehler et al. 2016;Saleem and Iglesias 2016). All these functions are included in the dimension named brand-centered human resources management, which is defined as "the human resources practices that make employees produce positive attitude and behaviors toward the brands of the firm" (Chang et al. 2012, p.629).
The recruitment process is the starting point of internal branding, thus organizations are invited to select people whose values are according to brand values (Saleem and Iglesias 2016). Firms need to attract applicants with a strong organizational fit Murillo and King 2019b) because they probably will exhibit better attitudes and behavior toward the brand . In this sense, human resources managers must design recruitment structures to select those candidates suitable for the brand values (King and Grace 2012).
Training programs are cataloged as a central component of internal branding ) because they train and educate employees on how to promulgate brand values proposed in the brand promise (Punjaisri and Wilson 2011). These programs allow employees to appreciate the basic notions of the brand and understand how their behavior affects brand equity (Poulis and Wisker 2016).  suggests that events, training sessions, coaching and mentoring can be implemented as branding training tools.
Brand rewards systems were also highlighted as an important factor within internal branding management (Iglesias and Saleem 2015; Piehler 2018; Punjaisri and Wilson 2011). Rewarding employees for their behavior toward the brand positively affects in delivering the brand promise to external customers (Saleem and Iglesias 2016). Likewise, these practices help to maintain brand standards by promoting attitudes consistent with brand values ). According to Foster et al. (2010), rewards systems support training processes because employees proactively internalize important aspects related to the brand. Hence, it is necessary to offer incentives for employees to strengthen the brand and to achieve corporate objectives (Anselmsson et al. 2016;Dechawatanapaisal 2018).
And finally, the human resources department must establish evaluation systems to monitor employee brand performance to correct the failures timely (Quaratino and Mazzei 2018). According to Chiang et al. (2018), brand-based performance evaluation should assess if employees display brand-related traits and attitudes (i.e., agreeableness, service orientation), behaviors (i.e., customer-oriented behaviors, helping others, team spirit), and those aspects related to performance (i.e., customer satisfaction, profitability). Furthermore, Lee et al. (2019) add that brand-based performance evaluation should be applied for leaders in terms of executive competence, brand communication skills, interpersonal relationships, and leadership through comments from themselves, subordinates, superiors, and colleagues.

Internal brand communications
Internal brand communications were the most mentioned dimension by authors. It is considered a key mechanism of internal branding (Sang and Swinney 2012), and its function is to transmit to employees a clear idea about the brand , improving their understanding and knowledge about the role they play in delivering the brand promise (Punjaisri and Wilson 2011). Sharma and Kamalanabhan (2012) state that internal brand communications induce brand identification of employees and promote a sense of unity over brand values. In addition, Biedenbach and Manzhynski (2016) ensure that good internal communications management facilitate the positive employees' perceptions about the firm, which in turn increases their level of organizational commitment.
Anees-ur-Rehman et al. (2018) stated that an effective internal brand management depends on a strategic design of internal brand communications through written messages and verbal and non-verbal signals that facilitate the understanding of the brand. Within the internal branding literature, specific internal communications techniques have been proposed, such as daily briefing, newsletters, corporate websites, groups meetings, brand manuals, notice boards, corporate videos, corporate magazines and brochures Dechawatanapaisal 2018;Du Preez et al. 2017;Hasni et al. 2018;Hoppe 2017;Punjaisri et al. 2009a). Additionally, Piehler et al. (2016) and Piehler (2018) recognize these techniques are effective for communicating relevant information about the brand, but they also emphasize the need to promote constant and fluid communication from managers to employees and vice versa.
On the other hand, it is necessary to affirm that internal brand communications must be supported by external brand communications to create congruence between internal and external brand messages (Pinar et al. 2016;Hofer and Grohs 2018). About this issue, Anees-ur-Rehman et al. (2018, p.305) express that "brand communication is essentially a communicative interaction process between employees, customers, and stakeholders in the co-creation of brand experience". For this reason, Saleem and Iglesias (2016) express that employees receive information about the brand from different sources, formal and informal, at an internal and external level. In this regard, it is clear that brand messages that employees receive come from different sources, however, messages transmitted within the organization constitute the main source for employees to understand and internalize all the information about the Brand ).

Brand leadership
All internal branding efforts would be in vain if organizations did not have leaders who motivate employees to translate brand values in reality (Dechawatanapaisal 2018). Leaders are key actors in developing an organizational brand climate and motivating their team to engage with the Brand . Managers are called to be leaders to guide their employees to achieve brand objectives (Poulis and Wisker 2016). Though, any member of the organization can become a brand leader who can motivate others to exhibit behaviors toward the brand . In this sense, Saleem and Iglesias (2016) affirm that brand leadership implies the existence of people within firms who act as transformational leaders that promote brand ideology and facilitate Brand understanding.
Du Preez et al. (2017) ensure that the role of brand leaders is to make employees internalize the brand as part of their identity. Leaders must strive to influence employees through internalizing brand values to motivate them to exhibit brand behaviors in-role and extra-role (Lee et al. 2019). Besides, leaders must identify and understand how employees receive information about the brand to ensure that all messages are consistent with the brand image ). Thus, leaders should promote the brand within the organization under a unique message that guides employees to exhibit brand behaviors.
The positive impact of brand leadership on the internal branding process can be confirmed by Xie et al. (2016), who found that leadership is positively related to employee brand building behavior, which in turn generates favorable customer perceptions about the brand. Uen et al. (2012) also empirically demonstrated that transformational leadership positively influences the development of brand organizational climate and employee brand behavior. If employees know and understand the brand, their daily functions will be able to "live the brand" to external customers and also to promote brand leadership at all levels in the organization (Du Preez and Bendixen 2015).

Outcomes of internal branding
The review of the concept and dimensions of internal branding revealed that it generates positive outcomes for firms. Some authors (Aydon 2009;Biedenbach and Manzhynski 2016;Helm et al. 2016) refers to purely internal benefits, especially for employees; but other authors Coleman et al. 2015; Erkmen and Hancer 2015; Poulis and Wisker 2016; Sang and Swinney 2012) recognize internal benefits, but they emphasize that the ultimate outcomes are projected to external sector, specifically to customer satisfaction and building of brand equity. Punjaisri et al. (2009b) consider that internal branding has a positive impact on the attitude and behavior of employee to deliver the brand promise. Their findings demonstrated that internal branding positively influences brand identification, brand engagement, and brand loyalty in employees.
These findings were also supported by Dechawatanapaisal (2018), who provided empirical evidence confirming that internal branding promotes brand identification and brand commitment. On the other hand, Du Preez et al. (2017) showed in their study that internal branding not only influences brand commitment and brand citizenship behaviors, but also job satisfaction and intention to stay in the organization. Brand citizenship behavior is also supported by Piehler et al. (2016), who also identified brand understanding, brand identification, and brand commitment as outcomes of internal branding.
From another perspective, Hasni et al. (2018) affirm that internal branding contributes to deliver the brand promise by employees, generating a positive impact on-brand equity. Their statistical findings confirm that internal branding plays a crucial role in creating customer-based brand equity because if employees have the skills and motivation they need to deliver the brand promise, they can fulfill the expectations of customers, which in turn increases brand equity. Similarly, Punjaisri and Wilson (2011) state that internal branding impacts directly on employees' ability to deliver the brand promise, and as a result, they improve their brand performance. They also add that personal variables such as age, educational background, and length of service, influence how internal branding impacts on employees.
The above paragraphs evidenced that there is also a discussion about the outcomes of internal branding. Table 3 shows the outcomes identified in this literature review.
According to the information presented in Table 3, it is noted that brand commitment, brand citizenship behaviors, brand identification, brand equity, and brand loyalty, are the main outcomes of internal branding. Brand knowledge was identified as an important consequence of internal branding; however,  ensures that brand knowledge is part of a multidimensional concept named brand understanding, which also includes other components that must be considered within the outcomes of internal branding. For this reason, this review will consider brand understanding instead of brand knowledge. Job satisfaction was also identified as a consequence of internal branding; however, some authors Du Preez et al. 2017;Iyer et al. 2018;Saleem and Iglesias 2016) consider it as a secondary positive effect of internal brand management because the main focus of internal branding is not employee satisfaction, but brand-related outcomes among employees. On the other hand, intention to stay was also identified as a consequence of internal branding; however, this benefit can be considered as brand loyalty.
In summary, the principal outcomes of internal branding identified in this literature review are brand understanding, Table 3 Outcomes of internal branding identified by authors Outcome brand identification, brand commitment, brand loyalty, brand citizenship behaviors, and brand equity. Each of these results will be defined below.

Brand understanding
Brand understanding is defined as "employees' comprehension of brand-related information" (Piehler et al. , p. 1580. This concept has been used interchangeably with other terms such as brand knowledge, internal brand knowledge, corporate brand knowledge, or knowledge of desired brand image (Murillo and King 2019a). However,  ensures that brand understanding is a multidimensional concept that should not be limited only to brand knowledge. The author expresses that brand understanding include four dimensions: (1) brand relevance (employees understand that the brand is important to the organization's success); (2) behavior relevance (employees understand that they contribute, through their behavior, to the brand's success); (3) brand knowledge (employees are informed about the brand and they know what it represents); and (4) brand confidence (employees can translate abstract brand identities and brand promises into specific, brand strengthening behaviors in their daily work). Murillo and King (2019a) state that brand understanding is achieved when employees appropriate explicit knowledge such as mission, vision, brand values, among others, but also tacit knowledge when employees engage with the brand from their personal beliefs. If employees understand the brand, they will surely show positive behaviors toward the brand because they know how to do it . In this sense, more than just having information about the brand, internal branding make employees have a deep understanding of all aspect related to the brand, and the role they play in brand success.

Brand identification
Brand identification is another important outcome of internal branding, and it is also a consequence of understanding the Brand . Brand identification has been defined from the social identity theory as a specific form of organizational identification . According to Saleem and Iglesias (2016), brand identification is a psychological membership that employees feel toward the brand as a sense of belonging. Piehler et al. (2016) affirm that brand identification have a cognitive component and an affective component: "cognitive identification refers to the extent to which people perceive themselves as belonging to an organization. Affective identification instead is the extent to which people have positive feelings about being part of an organization" (p.1579).
In this sense, if employees identify with the brand, they will feel a personal attachment to the brand, what makes them exhibit a better performance in-role and extra-role Ngo et al. 2019). Likewise, employees who are identified with the brand will show strong support for achieving organizational objectives in terms of brand management . The above statements can be validated thanks to Punjaisri et al. (2009a) and Piehler et al. (2016), who empirically demonstrated that brand identification is an antecedent of employee brand commitment. For this reason, organizations need to manage brand identification, even more in service companies ). Thus, internal branding is a critical tool to promote unique and distinctive brand values that help employees to internalize and promote their brand identification (Foster et al. 2010).

Brand commitment
Brand commitment is the psychological attachment employee feel toward the Brand (King 2010). According to Schulz et al. (2017), the literature identifies three different forms of organizational commitment (i.e., affective, continuance and normative), but the affective commitment has the major effect on employee performance because it represents their intention to strive for the organization success and motivation to support its mission, objectives, and values. In fact,  ensures that brand commitment is an affective consequence of internal branding and it should be classified as a unidimensional construct that reflects the emotional link between employees and brands. Committed employees are expected to have positive perceptions of the organization and to feel motivated to achieve organizational objectives (Biedenbach and Manzhynski 2016) because brand commitment makes employees improve their performance , resulting in greater customer satisfaction ) and brand success (King and Grace 2012).
On the other hand, Kimpakorn and Tocquer (2010) recognize that brand commitment begins with employee brand identification and their motivation to make an additional effort to achieve brand objectives, resulting in their intention to stay. When employees share their faith with the brand, they are expected to generate an emotional attachment to the brand, thereby increasing their intention to stay. In this sense, if employees feel committed to the brand, they will be loyal to the organization, reducing turnover levels (Skaalsvik and Olsen 2014;Watson et al. 2018). That is why brand commitment is considered an antecedent of brand loyalty (Punjaisri et al. 2009a, b).

Brand loyalty
Loyalty is a key indicator of successful relationships, either with employees or with customers. If a firm achieves the loyalty of their employees, in response, they will work for customer loyalty . Therefore, one of the objectives of internal branding is to ensure that employees are loyal to the brand so that they can successfully represent the brand to customers through their behavior (Poulis and Wisker 2016). From the theory of internal branding, brand loyalty is defined as the intention of employees to remain in the organization . This intention to stay is the result of the psychological contract that employees develop with the Brand (Saleem and Iglesias 2016).
The literature notes that some authors (Dechawatanapaisal 2018;Du Preez et al. 2017;Karatepe 2015;Ragheb et al. 2018;Watson et al. 2018) do not use the term "brand loyalty", but they mentioned "intention to stay", however, both concepts have been used interchangeably as the intention of employees to remain in the organization. Brand loyalty has become an important factor for organizational success because it reduces turnover intention, saving time and financial costs . Punjaisri et al. (2009b) explains that brand loyalty is critical because "it drives down costs through reduced recruitment and training expenditures and all the cost efficiencies which accrue from skilled workers who are up to speed and familiar with both the tasks at hand and their customers, thereby improving an organization's profits" (p.213). For this reason, Du Preez and Bendixen (2015) and Hasni et al. (2018) recommend implementing internal branding to guarantee greater job longevity and positive outcomes in terms of brand management.

Brand citizenship behaviors
The internalization of brand values by employees is demonstrated through attitudes and behaviors (King and Grace 2012). Thus, the main consequence that managers seek when implementing internal branding is to achieve that employee behaviors are aligned with the Brand (Murillo and King 2019b). If employees internalize the attributes of the brand, they will naturally be able to express these attributes through their behavior to external customers, fulfilling their expectations regarding the brand (Poulis and Wisker 2016).
Based on the above statements, brand citizenship behaviors as one of the principal objectives of internal branding. It is defined by Piehler et al. (2016) as "all employee behaviors that are consistent with the brand identity and brand promise such that together they strengthen the Brand" (p. 1577). According to Quaratino and Mazzei (2018) and Ruediger et al. (2012), different terminologies have been used to refer to brand citizenship behaviors, for example, brand supporting behaviors, or brand-adequate behavior, brand consistent behaviors, behavioral branding, and brand-aligned employee behavior, however, these terms refer to all those verbal or non-verbal behaviors that determine the experience and brand value.
About this subject,  states that the diversity of actions that integrate brand citizenship behaviors make it a multidimensional construct that include: (1) brand compliance, which means following the rules to maintain the brand; (2) brand endorsement, which involves representing the brand favorably, and also recommending it and defending it to potential customers, other employees, and other stakeholders; and (3) brand development, which includes behaviors that promote brand improvement, such as developing expertise, participating in training, developing ideas, taking over extra duties and responsibilities, or making suggestions to improve customers' brand experience. In consequence, all of these brand behaviors facilitate to fulfill the brand promise to external customers.

Brand equity
The concept of brand equity can be defined from a financial or marketing perspective. In financial terms, brand equity is the monetary value of a brand that may be useful for a merger, acquisition, or divestiture purposes, however, from a marketing perspective, which is considered for internal branding purposes, brand equity refers to how customers perceive the brand and how they build value about it in their minds (Kimpakorn and Tocquer 2010). Employees are critical actors in building brand equity because they represent the brand to customers and other stakeholders through their behaviors Erkmen and Hancer 2015;Schlager et al. 2011). In fact, some authors (Poulis and Wisker, Anees-ur-Rehman et al. 2018;Poulis and Wisker 2016;Skaalsvik and Olsen 2014) state that building brand equity begins when organizations adopt an internal approach to brand management to promote the brand among their employees.
Brand equity has been identified as the final consequence of internal branding (Anees-ur-Rehman et al. 2018;Poulis and Wisker 2016). It means each of the brand actions oriented toward employees generates a set of outcomes, which in turn builds brand equity (Pinar et al. 2016). Although employees are the target group for internal branding, it is expected that long-term consequences will be projected externally by strengthening the brand. From this perspective, Sang and Swinney (2012) summarize internal branding as the alignment of employees' attitudes and beliefs toward the creation of brand equity. These results can be validated by reviewing the findings of Hasni et al. (2018), who empirically demonstrated that internal branding helps employees successfully deliver brand promises and, in consequence, create brand equity among customers.

A proposal for a conceptual model of internal branding
After reviewing each of the elements of the conceptualization of internal branding in detail, this article attempts to propose a conceptual model based on the empirical evidence found in the literature review. Additionally, this study considered the importance given by authors to each element included in the conceptual model. Despite internal branding is still a developing subject, the conceptual model proposed in this study (see Fig. 1) represents a relevant contribution to consolidate knowledge generated about internal branding.
The structure used by Punjaisri and Wilson (2011) was taken as a reference to develop our conceptual model. Firstly, the model proposes that brand orientation and internal market orientation are organizational antecedents that facilitate the implementation of internal branding. Firms that adopt these two approaches will be more willing to implement internal branding programs because they consider brand management and the internal market as two key factors for their organizational success. Secondly, the model presents internal branding as a cross-functional effort between marketing and human resources departments, and it is composed of three dimensions: (1) brand-centered human resources management, which in turn includes brand-oriented recruitment, branding training programs, brand rewards systems, and brand-based performance evaluation; (2) internal brand communications, and (3) brand leadership. And, thirdly, the model highlights the outcomes of internal branding. The consequences for employees are brand understanding, brand identification, brand commitment, brand loyalty, brand citizenship behaviors, and then these outcomes make employees build brand equity to external stakeholders. The sequence in outcomes of internal branding show in the conceptual model is supported by the empirical evidence found in the literature. Piehler et al. (2016) empirically demonstrated that brand understanding has positive effects on-brand identification, and in turn, brand identification influences brand commitment. According to Punjaisri et al. (2009b), brand commitment is a precursor of brand loyalty because they found that employees who are committed to the brand exhibit loyalty toward the brand, in terms of their intention to stay. There were not found empirical evidence to demonstrate the relationship between brand loyalty and brand citizenship behaviors, but some research Piehler et al. 2016) found that brand commitment does impact brand citizenship behaviors.
Based on the elements included in the conceptual model, this study proposes the following definition of internal branding: Internal branding is a cross-functional process between the marketing and human resources departments, which focuses on managing the brand within the organization through brand-centered human resources management, internal brand communications, and brand leadership, with the objective of achieving brand consequences in employees (brand understanding, brand identification, brand commitment, brand loyalty, and brand citizenship behaviors), so that they can build brand equity to external stakeholders.
The above definition is significant because it includes the most relevant elements within the internal branding process. On the one hand, the definition responds to "what" when it highlights that internal branding is a cross-functional process between marketing and human resources departments. On the other hand, the definition responds to "how" when it details all dimensions required to implement internal branding. And finally, the definition responds to "what for" when it identifies the outcomes of internal branding in employees and what they can build externally.

Brand-centred human resources management
Most of the definitions of internal branding show it from a general perspective; however, the definition proposed in this study considers the multidimensionality of internal branding in their components and outcomes, offering a comprehensive conceptualization. This study recognizes that further research on this issue is needed. However, the conceptual model and the definition proposed in this review can be considered a starting point to generate a unified vision of internal branding.

Some managerial implications of internal branding from this literature review
This study has highlighted that brand management not only involves external actions but also involves an internal orientation that seeks to promote the brand among employees. In this sense, managers must consider internal branding as a key process within their brand management strategy, which successfully complements all brand efforts made externally. Intending to contribute to the implementation of internal branding, this section will show some managerial implications.
First, this literature review found that the brand has become a strategic resource for organizations because, more than a name or symbol, it can represent a source of competitive advantage. For this reason, organizations must adopt a brand orientation, making the brand a strategic resource to achieve business success. On the other hand, this study also invites organizations to adopt an internal market orientation because employees are key players in brand management because they represent the brand through their attitudes and behaviors. Firms that simultaneously adopt brand orientation and internal market orientation will be motivated to implement internal branding programs because they recognize the importance of brand management and the role that employees play in this process.
Second, this study identified that internal branding is a cross-functional process that involves marketing and human resources departments. Therefore, managers must strategically integrate these two areas when planning, executing, and monitoring brand management internally. Organizations must recognize that internal branding is not the sole responsibility of the marketing department due to some processes are under the domain of the human resources department (brand-oriented recruitment, branding training programs, brand rewards systems, and brand-based performance evaluation).
Third, this study recommends that managers must implement internal branding following three specific dimensions: 1. Brand-centered human resources management. Some functions of the human resources area must be carried out according to the brand. Firms need to design recruitment structures according to the brand to hire employees who adequately fit with brand values. This process implies use scales to measure how much a job candidate fits with the brand, and also implies to follow the brand performance of new employees during their trial period. Likewise, it is necessary to train employees on how they should represent the brand through their daily tasks. Also, the human resources department should create brand rewards systems to compensate employees for their results toward the brand. The rewards can be financial, in species, or recognition in front of others. Finally, employee performance should be evaluated considering the individual and/or group performance toward the brand. 2. Internal brand communications through daily briefings, newsletters, corporate websites, meetings, brand manuals, bulletin boards, corporate videos, brand books, and corporate magazines are useful mechanisms to transmit to employees a clear idea about the brand and what it represents. 3. Brand leadership as a strategy to develop leaders willing to promote the brand within the organization. This does not exclusively involve managers, but also employees who have the skills to influence others.
And fourth, this literature review proposes that organizations must implement internal branding due to its outcomes among employees, and also for its consequences at the external level. The literature showed empirical evidence that demonstrates the positive effects of internal branding on employees in terms of brand understanding, brand identification, brand commitment, brand loyalty, and brand citizenship behaviors. And then, all of these outcomes motivate employees to build brand equity for external publics. Thus, internal branding is a fundamental requirement within the brand management strategy because if employees properly internalize the brand, they will be able to represent it in front of external stakeholders, building brand equity.

Opportunities for future research in the field of internal branding
Traditionally, external branding has received more attention from researchers and professionals (Hytti et al. 2015;Wagner and Peters 2009). Some authors (Hytti et al. 2015;King and Grace 2010;Piehler et al. 2018;Saleem and Iglesias 2016;Zhang, et al. 2016) consider that internal branding is a subject still in developing. For this reason, the last section of this paper aims to offer a guide for future research in the field of internal branding.
Initially, it is convenient to analyze the industries where research about internal branding has been carried out. This review noted that studies about internal branding have been developed in various industries, however, some of them catch more attention than others. For example, the hotel industry gathered the largest number of paper in this review Chiang et al. 2018;Cheung et al. 2014;Kimpakorn and Tocquer 2010;Punjaisri et al. 2009a;Punjaisri and Wilson 2011;Sevel et al. 2018;Uen et al. 2012), followed by the financial industry Du Preez and Bendixen 2015;Lee et al. 2019;Pinar et al. 2016;Ragheb et al. 2018;Schmidt and Baumgarth 2018). Other service industries such as universities (Whisman 2009;Yousaf and Li 2015), hospitals (Hoppe 2017(Hoppe , 2018Hytti et al. 2015), restaurants (Murillo and King 2019a, b;Watson et al. 2018), and airlines (Erkmen and Hancer 2015), were identified in this review. Additionally, other authors Ghose 2009;King andGrace 2010, 2012) developed their studies in service companies, but they did not specify what type of industry.
The above details show that service industries concentrates most of the researches included in this review. This results could be explained according to Du Preez and Bendixen (2015), Kimpakorn and Tocquer (2010) and Ragheb et al. (2018), who affirm that internal branding acquires relevance in service firms because the brand experience is built through interactions between customers and employees in each service encounter. However, this literature review also found studies in the B2B sector (Anees-ur-Rehman et al. 2018;Anisimova and Mavondo 2010;Biedenbach and Manzhynski 2016;Coleman et al. 2015;Dechawatanapaisal 2018;Sandbacka et al. 2013;Zhang, et al. 2016), what demonstrates the importance of internal branding in this sector. The brand has become a key factor for any company, therefore, internal and external brand strategies are relevant in the B2B sector as much as the B2C sector (Skaalsvik and Olsen 2014;Zhang et al. 2016). Supporting this idea, Piehler et al. (2018) recommend future research to investigate the implications of internal branding in the B2B sector compared to B2C. Thus, there is an opportunity to carry out more research about internal branding in the B2B sector. Some research questions in this field could be: What role does internal branding play in B2B firms?, What particularities of the B2B sector can limit the success of internal branding in these types of firms?, What dimensions of internal branding acquire greater relevance in the B2B sector? Is there any difference between outcomes of internal branding for B2B firms compared to B2C ones?, How does internal branding affect brand equity in B2B firms?
The public sector is another context to explore from the perspective of internal branding. Only two studies about this issue were found in this literature review. One of them was the research of Sharma and Kamalanabhan (2012), who investigated the impact of corporate internal communications on internal branding from the perception of Indian public sector employees. The other research was developed by Hytti et al. (2015), who studied the challenges in delivering the brand promise in municipal hospitals. To find a few papers about internal branding in the public sector represents an opportunity for future research because public sector firms run under particular conditions, which would be interesting to investigate. In this sense, this study proposes the following research questions: How would internal branding be implemented in the public sector, considering the variety of organizations included in this sector?, What challenges do public sector firms face in implementing brand-centered human resources management, considering their special conditions to recruit and compensate?, What outcomes do public sector firms expect to achieve by implementing internal branding?
Sustainability is another topic that also represents an opportunity for future research in the field of internal branding. Few studies involving this issue were found in this review (App and Büttgen 2016;Biedenbach and Manzhynski 2016). Sustainability acquires importance in the field of marketing, so it must be considered within the investigation of internal branding. The findings of Biedenbach and Manzhynski (2016) demonstrated that employees who reflected a high level of brand knowledge and brand commitment, also perceive the importance of sustainability for the firm. The authors state that internal branding improves the awareness of employees about sustainability and facilitate their positive evaluations of the company's sustainability performance. For this reason, at the end of their paper Biedenbach and Manzhynski (2016) invite to investigate more about the relationship between internal branding and sustainability. Here are some research questions about it: How is the process of promoting the brand and sustainability simultaneously through internal branding?, How does internal branding affect sustainability performance in organizations?, What dimensions of internal branding allow employees to align with sustainability?, Is there any difference in implementing the internal branding process in sustainability-oriented companies compared to those that do not?
The literature review also showed that most of the studies on internal branding are focused on employees' perspectives. Few studies from customers' perspectives were found in this review (Anselmsson et al. 2016;Chang et al. 2012;Chiang et al. 2018;Kang 2016), Kimpakorn and Tocquer 2010). That is why some authors (Erkmen and Hancer 2015;Piehler et al. 2018;Pinar et al. 2016;Sharma and Kamalanabhan 2012) suggest to include the customers' perspectives to measure the impact of internal branding on external publics. Piehler et al. (2018) recommend empirically investigating the effects of internal branding on organizational performance, in terms of what customers perceive and financial performance. In response to the above, the following research questions are proposed: How do external customers perceive the implementation of internal branding in their interactions with employees?, How do customers influence the information that employees receive about the brand?, How do external customers perceive the outcomes of internal branding in terms of their satisfaction?, How can firms measure the impact of internal branding on-brand equity in customers and other stakeholders?, How does internal branding impact organizational financial performance?
In methodological terms, the literature review showed that most of the studies were developed under cross-sectional designs. Only two studies included in this review used longitudinal designs (Murillo and King 2019a;Schmidt and Baumgarth 2018). For this reason, it is necessary to extend the methodologies used to study internal branding. Several authors (Anees-ur-Rehman et al. 2018;Anselmsson et al. 2016;App and Büttgen 2016;Bravo et al. 2017;Chang et al. 2012;Chiang et al. 2018;Coleman et al. 2015;Dechawatanapaisal 2018;Gammoh et al. 2018;Hasni et al. 2018;Hoppe 2018;Hytti et al. 2015;Iyer et al. 2018;Lee et al. 2019;Murillo and King 2019a, b;Ngo et al. 2019;Piehler et al. 2018;Punjaisri and Wilson 2011;Uen et al. 2012;Watson et al. 2018) highlighted the need to conduct research using longitudinal designs to analyze changes or evolutions over time. Using this design, Murillo and King (2019a) investigated the drivers of employee brand understanding in a restaurant chain for 7 months. They found that branding understanding runs through distinct stages over time, so differentiated internal branding actions are needed to consolidate brand knowledge in the long term.
In this sense, they demonstrated that longitudinal studies offer significant findings to the theory of internal branding, and also provides practical implications for managers. On the other hand, Ngo et al. (2019) and Piehler et al. (2018) also suggest carry out studies using experimental designs to analyze causal relationships when some variables within the internal branding process are manipulated. Thus, this review suggests some research questions: What are the outcomes of internal branding at different time intervals?, How do the dimensions of internal branding behave over time?, How would a differentiated internal branding process be implemented, and what would its implications be?, How are the cause-effect relationships between the antecedents, dimensions and outcomes of internal branding if they are analyzed from experimental designs?
The sampling procedure was another methodological aspect for improvement in future research. Most of the papers included in this review apply non-probabilistic sampling, even, some research Du Preez and Bendixen 2015;Erkmen and Hancer 2015;Hytti et al. 2015;Murillo and King 2019a;Punjaisri et al. 2009a;Sandbacka et al. 2013;Schmidt and Baumgarth 2018;Sevel et al. 2018) corresponded to case studies carried out in particular contexts. This is why some authors Cheung et al. 2014;Helm et al. 2016;Pinar et al. 2016;Ragheb et al. 2018;Xie et al. 2016;Yousaf and Li 2015) invite to investigate using probabilistic samples to get representative findings. Likewise, this review identified the need to investigate internal branding in different sectors, countries, and cultures in order to achieve significant generalizations in its theory. As Piehler et al. (2018) summarize, most of the empirical studies of internal branding have focused on individual organizations or small groups of firms, limiting the opportunity to generalize the findings. Therefore, future research should focus on replicating previous studies in other contexts to reaffirm or adjust the findings. Researchers can also conduct studies that simultaneously include different cultures and countries to generalize their findings.
Other opportunities for future research were identified in the conceptual approach analyzed in this study. Initially, it was found there is no consensus about the historical antecedents of internal branding. This discussion represents an opportunity to explore the beginning of internal branding through a bibliometric study or a literature review. Also, additional research is needed to analyze the antecedents of internal branding. This review proposes that brand orientation and internal market orientation are the antecedents of internal branding, however, this statement must be validated with further empirical evidence.
On the other hand, this literature review found diverse opinions about the dimensions of internal branding. The consolidation of the different contributions allowed identifying brand-centered human resource management, internal brand communications, and brand leadership as the main dimensions of internal branding. However, this review identified other components (internal brand communities, brand ideologies, brand ambassador programs, brand promotional products, sponsorship) that could be considered for future research to explain deeply how each one influences on internal branding.
The conceptual model proposed in this study is the result of a literature review, therefore, future research is needed to empirically validate the relationships established between the antecedents, dimensions, and outcomes of internal branding. Also, researchers can study the moderating effects between elements included in the conceptual model.
Finally, this review supports the recommendation made by Piehler et al. (2018), who invite to expand the research framework of internal branding to the context of multiple brands, considering that some firms act under this model. Traditionally, internal branding research has focused on corporate branding, but multiple brands represent an issue that should be investigated.

Concluding remarks
Internal branding has acquired relevance in recent years due to the importance of brand management for organizations. Previous studies criticized there was no consensus among authors about the definition of internal branding, and they invited to investigate more about it to consolidate its theory. For this reason, this paper aimed to explore the conceptualization of internal branding and also offers opportunities for future research.
This study identified different perspectives about the definitions of internal branding, although similarities found among authors allowed to conclude that internal branding is a cross-functional process between the marketing and human resources departments, which focuses on managing the brand among employees to make them build brand equity externally. The objective of internal branding is to promote the brand internally so that employees can successfully represent it to customers and other external audiences.
Thanks to the literature review, this study developed a conceptual model of internal branding that identifies the main antecedents, dimensions, and outcomes of internal branding. Brand orientation and internal market orientation were identified as the organizational antecedents of internal branding. Brand-centered human resource management, internal brand communications, and brand leadership were identified as the main dimensions of internal branding. These dimensions determine the implementation process, which must be supported by a cross-functional effort from the marketing and human resources departments. In terms of consequences, this review found that brand understanding, brand identification, brand commitment, brand loyalty, and brand citizenship behaviors are the main outcomes of internal branding, and in turns, these outcomes make employees build brand equity in front of external stakeholders.
The last section of this paper showed that internal branding offers various opportunities for future research. This review showed some contexts where internal branding has not been thoroughly investigated (i.e., some industries, sectors or countries, from the perspective of external actors, the field of sustainability, or the context of multiple brands). Furthermore, it is necessary to consider some methodological aspects to diversify how researchers obtain their findings and also achieve significant generalizations about internal branding. The conceptual model proposed in this study can be considered a relevant contribution to the conceptualization of internal branding, however, researchers are called to empirically evaluate the relationships established in the model. Finally, this study aimed to consolidate the knowledge available in the literature to offer a conceptualization of internal branding. The proposed conceptual model is a starting point to unify the fragmented ideas about internal branding, however, the discussion is still open so that other researchers can contribute to building a unified definition of internal branding.