Digital transformation and marketing: a systematic and thematic literature review

This article provides a systematic review of the extensive and fragmented literature focused on Digital Transformation (DT) and marketing by identifying the main themes and perspectives (i.e., employees, customers, and business processes) studied by previous research. By mapping the DT literature in the area of marketing, 117 articles, published between 2014 and 2020, have been identified. Through the adoption of a content analysis process, a multi-dimensional framework synthesizing the DT and marketing binomial has been provided. Results identify two thematical patterns: the macro-themes, related to the main digital technologies adopted within the marketing function, and the micro-themes, related to the effect/impact of these technologies on marketing processes and activities. Concerning the micro-themes, findings show how they have mainly studied from the customer and business processes’ perspectives, thus identifying an interesting research gap related to the analysis of the DT-marketing phenomenon from the employees’ standpoint. Based on these results, the paper derives a research agenda by also providing theoretical and managerial implications. Theoretically, it is the first systematic and thematic review focused on DT and marketing. In particular, it analyses this binomial from a broad and comprehensive perspective, thus offering a synergistic framework of the existing literature, which allows an inclusive vision and understanding about the phenomenon. At the managerial level, the paper could help organizations to enhance their awareness about marketing areas and processes that could better benefit from digitalization, thus driving the overall transition of firms towards DT.


Introduction and background
Over the last decades, digital transformation (DT) has received growing attention in the business literature since it represents a prominent feature for organizations to be leaders of change and competitive in their domain (Kraus et al., 2022). At once, in light of the COVID-19 pandemic, the DT phenomenon has experienced an abrupt acceleration (Priyono et al., 2020), as firms and organizations are forced to redesign their strategies and operating models through a massive adoption of technologies in order to respond to the crisis-caused changes (Hai et al., 2021;Hanelt et al., 2021). Therefore, the necessity of analysing the DT topic has become ever more crucial in the last few years.
Conceptually, DT refers to all changes that digital technologies can bring in a firm's business model, concerning products, processes, and organizational structures (Hess et al., 2016). Starting from this definition, it appears clear the pervasiveness of this phenomenon, which represents a real transition toward a new reality made of risks and challenges (Horvat and Szabo, 2019; Kraus et al., 2022;Vial, 2019). DT, indeed, can change every aspect of business, especially the marketing one (Caliskan et al., 2020).
Notably, the connection between DT and marketing has become ever more decisive in the last two years. The critical changes related to the COVID-19 crisis have particularly altered the firm and consumer relations, forcing companies to modify their marketing strategies through the massive exploitation of the digital technologies. In particular, marketing currently represents one of the main functions requiring to be adapted to the DT in order to protect firms' competitiveness (Caliskan et al., 2020). By following this research stream, some authors have tried to synthetize the main impacts of DT on marketing practices (Shkurupskaya and Litovchenko, 2016;Sunday and Vera, 2018), including (i) The increasing spread of information and communication technology (ICT) in the marketing communication channels; (ii) The opportunity to adopt real-time communication with customers; (iii) The development of new relationships between producers and consumers; (iv) The increasing effectiveness of the marketing activities through the monitoring of real-time data. Meanwhile, other authors have specifically focused their attention on the main digital technologies able to offer significant benefits to the marketing function (Ardito et al., 2019;Cluley et al., 2019;Giannakis et al., 2019;Ungerman et al., 2018) by also categorizing them on the basis of the marketing mix (Caliskan et al., 2020).
Despite the DT-marketing topic has received growing attention, to date, no systematic review exists concerning the analysis of the DT phenomenon with specific application to the marketing processes and activities. Notably, several studies have tried to review the DT literature from very restricted research areas (Hanelt et al., 2021) different with respect to the broader one of marketing, such as B2B relationships (Hofacker et al., 2020), business model innovation (Favoretto et al., 2022;, accounting (Knudsen, 2020), multinational enterprises (George and Schillebeeckx, 2022), leadership (Carvalho et al., 2022;Henderikx and Stoffers, 2022), quality management (Dias et al., 2021;Thekkoote, 2022), production applications (D' Almeida et al., 2022), business management adaptability (Zhang et al., 2021), stakeholder management (Prebanić and Vukomanović, 2021), and sustainability (Gomez-Trujillo and Gonzalez-Perez, 2021). Faced with this context, some authors have tried to analyse and systematize the previous DT literature within broader research areas such as the business and management (Kraus et al., 2022) and the organizational change (Hanelt et al., 2021). However, despite these contributions, until now, no study has focused on reviewing the literature dedicated to the binomial DT-marketing.
Starting from these assumptions, the present study aims to provide a comprehensive review of the extant literature focused on DT in the marketing area by identifying the main themes and perspectives of analysis. More in detail, the paper addresses the following research questions: (i) What themes have been studied by previous research on DT in the field of marketing? (ii) What are the main perspectives adopted by the research on DT in the field of marketing?
To answer these research questions, the study has been organized in two phases: while in the first one the DT literature has been mapped by focusing on all studies addressing the digital transformation and marketing topics during the period 2014-2020, in the second phase a synergistic framework with the main macro and micro themes characterizing DT in the marketing area (concerning the digital technologies use and effects, respectively), along with the related analysed perspectives, has been provided.
By doing so, this study informs the academicians about the recent evolution of DT literature on marketing-related topics. Additionally, by proposing a synergistic framework of results, the paper provides a solid support for discussing and delineating future research directions. Finally, the main results of this review could help organizations to increase their awareness about marketing areas and processes that could better benefit from digitalization, thus driving the overall transition of firms towards DT.
The remainder of the paper is structured as follows. Section 2 presents the methodology and Sect. 3 outlines the descriptive and thematic results of the study. Section 4 provides theoretical and managerial implications and proposes future research directions based on the main gaps in existing literature. Finally, Sect. 5 concludes the study by also discussing the main limitations.

Methodology
This study adopts the systematic review method (Tranfield et al., 2003) to detect, classify, and interpret "all the available research relevant to a particular research question, or topic area or phenomenon of interest" (Kitchenham, 2004;p. 1). Structurally, the review process has been divided into three phases: (i) Data collection; (ii) Paper selection; (iii) Content analysis.
The identification of specific keywords and terms represents the first systematic review step (Tranfield et al., 2003). In our research, the following string has been adopted: ["Digital transformation" AND "marketing"], with the final aim of identifying all the contributions simultaneously focused on these two topics,

Results and discussion
In the following sub-paragraphs, the descriptive and thematic results of the literature review will be presented.

Descriptive results
Concerning the yearly research trend (Fig. 2), a growing interest in the digital transformation-marketing topic emerged during the time-period under review. Particularly, we went from only one contribution published in 2014 to three in 2017; starting from 2018, the attention increased with 13 published articles, while the most significant peaks have been reached between 2019 and 2020, characterized by the higher production of contributions (45 in 2019 and 50 in 2020). Table 2 ranks the sources with the highest number of published contributions focused on the investigated topic. Ninety-three sources have published the 117 reviewed papers with the more relevant contribution from the Advances in Intelligent Systems and Computing (3,4%), followed by Industrial Marketing Management (3,4%), and IOP Conferences series: Materials Science and Engineering (3,4%), Communications in Computer and Information Science (2,6%), and Journal of Physics (2,6%).
Additional sources with only one published contribution are shown in Table 3. Notably, fifty-seven sources are Journals, eighteen are conference proceedings, and two sources are book series. Concerning the Journals, those from a domain especially related to the business management, society, technology innovation, economics, and engineering have shown interest toward this specific issue. With respect to the conference proceedings, the main fields of study concern the smart trends, technology innovation management, computer science, and information systems. Finally, regarding the book series, they are specifically focused on the information and communication and tourism research streams. The source's distribution is informant about the main future publication opportunities in the area of DT and marketing. Equally relevant is the result related to the contributions' ranking per citation since it allows to figure out the widespread and dissemination of the analysed research stream. Table 4 shows the top-ten contributions in terms of citations. Notably, the more cited contributions are very recent (published between 2019 and 2020) and mainly focused on the following topics: technological innovations as enablers for firms' digitalization strategies (Ballestar et al., 2019;Gil-Gomez et al., 2020;Hausberg et al., 2019;Peter et al., 2020;Sestino et al., 2020;Ulas, 2019;Yigitcanlar et al., 2020) and business sustainability (Sivarajah et al., 2020), and the impact of the COVID-19 crisis on consumers' (Kim, 2020) and firms' digital behaviours (Almeida et al., 2020).

Macro-themes related to the use of digital technologies
The identification of the most investigated digital technologies analysed in the marketing domain by the reviewed contributions represents the first result deriving from the content analysis. Appendix 1 displays the list of technologies along with their main conceptualizations. As shown in Table 5, the majority of contributions (67,1%) have focused their attention on the analysis of specific digital tools. In particular, the social media channels (social media marketing) represent the most examined technology (being investigated by 9,4% of the selected studies), followed by Big Data (8,7%), mobile marketing (i.e., mobile technology and smart apps) (8,1%), Internet of Things (6,7%), Artificial Intelligence (6,7%), and Industry 4.0 (6,7%). The remaining technologies (i.e., Machine learning; Online collaborative/support platforms/systems; Virtual/Augmented Reality; Websites/SEO; Cloud infrastructures; Chatbots; Drones/Smart robots; Security Protection systems; 3D print) have experienced a reduced interest by the extant literature (less than 6% of the identified contributions). Finally, a not negligible percentage of studies (32,9%) has analysed the topic of digitalization without investigating specific technologies. Rather, they broadly referred to the "digitalization phenomenon" as an overall macro-theme investing the marketing area. The sum of the identified macro-themes (n = 149) exceeds the number of papers analysed during the review process (n = 117) since some papers have simultaneously examined more than one macro-theme.
Specifically, three main perspectives emerged from our study, namely employees, customers, and business. While the employee perspective focuses on the human resources and their coexistence with new technologies, the customer one is mainly related to the digital opportunities offered on the consumer side, especially concerning the overall shopping journey. Finally, the process-focused perspective is primarily concerned with the influence of digital technologies on the different business practices and procedures.

Macro-themes, micro-themes, and analysed perspectives: a combined overview
In this section, the macro-themes, micro-themes, and analysed perspectives will be combined with the final aim of building a comprehensive overview (Table 9). By focusing on the first macro-theme (i.e., social media channels), no studies have specifically examined it from the employee perspective, thus identifying an interesting research gap. Conversely, research widely underlined the key-role of these tools from the business processes and customer perspectives. Concerning the first one, different contributions highlighted how social media support a multitude of business processes (e.g., segmentation, brand positioning, promotion, advertising, buying, after-sales), thus improving firms and marketing performance (Al-Azani and El-Alfy, 2020; Kazaishvili and Khmiadashvili, 2020;Lestari et al., 2019;Melović et al., 2020;Rebelli, 2019;Safiullin et al., 2020;Sivarajah et al., 2020;Ulas, 2019;Van Osch et al., 2019). At once, an equally relevant number of studies has also examined the social media impact from the customers' viewpoint (Hahn, 2019;Kumar-Singh and Thirumoorthi, 2019;Rebelli, 2019;Yusmarni et al., 2020) by identifying the main advantages for them, such as their involvement and engagement in the value creation process and the access to personalized assistance services (Kazaishvili and Khmiadashvili, 2020;Sivarajah et al., 2020).
Big Data represent the second macro-theme extracted from the thematic literature review. These have been especially analysed from the business processes perspective, recognizing them as one of the most significant challenges and innovations of recent years within the DT framework. Almaslamani et al. (2020), for instance, explained how the Big Data adoption can lead firms to use intelligent market basket analysis, thus enhancing the relationship with customers. Similarly, the study of Miklosik and Evans (2020) analysed the impact of Big Data on the digital transformation of the marketing industry by examining the main challenges it faces from a data and information management viewpoint. At once, Sestino et al. (2020) provided interesting implications for marketers by underlining how the DT, enabled by Big Data, can positively influence many facets of business (e.g., collection of large-scale data allowing to identify emerging trends on consumer behaviour; creation of promotion campaigns with real-time data; creation of stronger bonds with consumers). By specifically focusing on the B2B market, the study of Sivarajah et al. (2020) demonstrated the Big Data capability to allow B2B firms to become profitable and  Sales processes (i) The impact of digital tools on the sales processes Production processes (i) Digital production systems/machines able to increase the process quality; (ii) The insertion of technologies in the automation and control of production processes Value co-creation/value proposition (i) Co-creation of value (with customers) remain sustainable through strategic operations and marketing-related business activities. Overall, the research offers interesting implications for all the stakeholders interested in understanding and exploiting the use of Big Data with the final aim of achieving business sustainability. As for mobile marketing (mobile technology and smart apps), research has mainly examined it by focusing on the customer perspective. Indeed, mobile devices have deeply influenced customers' behaviours and preferences toward online shopping (Sundaram et al., 2020) by also transforming them into an integral part of the value creation process. Meanwhile, mobile technology and smart apps have also been studied from the business processes viewpoint since they have become an excellent opportunity to analyse consumers in more meaningful manners, thus supporting the development of appropriate marketing strategies (Sundaram et al., 2020). Additionally, mobility, along with other digital technologies, is creating relevant opportunities for firms to transform themselves by impacting on their purchasing processes (Ulas, 2019) as well as on their distribution activities, since mobile apps represent omni-channel retail platforms allowing consumers to obtain products from different channels, such as e-commerce, modern markets, and traditional ones. In this way, the shopping experience streamlines and integrates itself across channels (Cahyadi, 2020). Conversely, even if the employee perspective has been less investigated, it represents an interesting field of study since the mobile technology is impacting, on a massive scale, the workplace (Attaran and Attaran, 2020). More in detail, it can raise employee engagement; increase productivity through the scheduling/automation of daily activities; enable real-time communications through different tools, such as group chats or one-to-one messaging. Moreover, the 5G advent could revolutionize the way employees work "in much the same way the Internet did in the 1980s" (Attaran and Attaran, 2020;p. 66). Notably, it can allow employees to (i) Fast  (2) Customer relationship management/customer connectivity/centricity (25) Customer Perspective (CP): 68 = 33,3% Customer experience/journey (17) Customer behaviour (11) Buying/consumption processes (6) Value co-creation/value proposition (5) Customer service (3) Neuromarketing (1) Digital metrics (18) Business process perspective (BPP): 97 = 47,5% Business process efficiency (17) Market knowledge (15) Communication policy (12) Product policy (9) Sales processes (6) Production processes (6) Supply chain processes (5) Branding (4) Export market orientation/export performance (2) Drivers/barriers/risks of digitalization (2) Social responsibility (1)

Table 9
Macro-themes, micro-themes, and analysed perspectives: a combined overview

Micro-themes
Analysed perspectives Social media channels /

Micro-themes
Analysed perspectives

Machine learning
Human resources (1)

CP (32)
Digital metrics (7) Business process efficacy (7) Market knowledge (5) Communication policy (4) Sales processes (3) Production processes (3) Product policy (2) Drivers/barriers/risk of digitalization (2) Branding (1) Export market orientation/export performance (1) Social responsibility (1) BPP (36) download and upload files and documents; (ii) Quicker move data; (iii) Carry the office anywhere; (iv) Exploit resources such as real-time video interaction and smart conference/meetings rooms, thus maximizing the workplace productivity and efficiency, reducing travel time, and saving operational costs for remote employees; (v) Increase office collaboration; (vi) Synchronize and access to large amounts of data storage. Another macro-theme widely analysed by the literature focused on the DT and marketing is Internet of Things, which represents one of the main megatrends related to the technological revolution (Hamidi et al., 2020). Extant research (e.g., Almeida et al., 2020;Chehri and Jeon, 2019) has particularly examined the main improvements provided by this technology in terms of business processes. Notably, Sestino et al. (2020) underlined how IoT can contribute to: (i) Design products/services based on consumers' consumption experiences; (ii) Collect consumption data useful, for marketing managers, to identify new gaps, trends, or variables in understanding consumer behaviour; (iii) Identify consumers' attitudes and choices on a large scale. At once, different studies (e.g., Almeida et al., 2020;Sestino et al., 2020) have also investigated the impact of IoT from the customer perspective by focusing on their ability to provide new types of services and high-quality products; as well as to improve the customer journey through more targeted promotions, announcements, and email marketing. Finally, even if the employee perspective represents the least investigated one, some authors (e.g., Almeida et al., 2020;Peter et al., 2020) identified several IoT advantages from this viewpoint, including the possibility of adopting mobile, flexible, team-oriented, and non-routine working methods, which allow the creation of digital workplaces; activating collaborative practices between all the staff's levels; and communicating and disseminating corporate strategies, thus creating innovative workplaces.
Concerning the Artificial Intelligence (AI), it has been analysed from all the perspectives, especially the customer and business processes ones. Different studies investigated the advantages of the AI-based digital humans for customers, including the possibility to obtain better knowledge of their preferences and needs (Kumar-Singh and Thirumoorthi, 2019), to build an innovative and real-time relationship with the firms (Cherviakova and Cherviakova, 2018), to experience a completely new and interactive journey, and to receive personalized offers (Ianenko et al., 2019). From the processes perspective, AI significantly influences marketing processes and activities (Almeida et al., 2020;Ianenko et al., 2019;Sargut, 2019) through the analysis of the customers' behaviours and the realization of more specific targeted profiles (Ianenko et al., 2019). AI also influences the distribution activities and, in particular, the automation of the ordering process of products and services (Cherviakova and Cherviakova, 2018). Moreover, by considering unexpected events, AI allows to recalculate new routes and to maintain constant contacts with clients and the logistics service providers. Literature (Cherviakova and Cherviakova, 2018) underlined the AI role in allowing the automatic placement of advertisements across channels, while Kumar-Singh and Thirumoorthi (2019) analysed the AI relevance also with respect to the buying/consumption process. Finally, it has been recognized the importance of AI with respect to both sales (Almeida et al., 2020) and after-sales processes, as it permits to better examine the customers' opinions about products/ services, and to identify their satisfaction level as well as the possible enhancements that could be applied to the firm's offering. Concerning the employee perspective, AI-by representing a disruptive technology-has significantly influenced the labour relations model and, in particular, the knowledge sharing among employees (Almeida et al., 2020;Subramani, 2019;Ulas, 2019). Therefore, it becomes fundamental to enhance the employee training toward this digital tool, which is becoming more and more integrated into the workplace (Yigitcanlar et al., 2020).
By representing a multifaceted term, the Industry 4.0 has emerged as an additional macro-theme related to the DT-marketing binomial. Notably, research (e.g., Chehri andJeong, 2019, Del Giorgio andMon, 2019;Hamidi et al., 2020) has mainly investigated this topic from the customer and business processes perspectives, especially by focusing on the main principles behind it, namely 5c (i.e., Cooperation, Conversation, Co-creation, Cognitivity, Connectivity). This technology has created the basis of the digital ecosystem, thus offering the key ability, for firms and customers, to exchange data in real-time (Nosalska and Mazurek, 2019). By specifically focusing on the business processes perspective, an interesting point of view has been provided by Naglič et al. (2020), who analysed the Industry 4.0 macro-theme in combination with the export market orientation/export performance micro-theme. The authors offered a framework on how companies can enhance their export performance through the knowledge related to the Industry 4.0. Overall, their study detected how firms that invest in digital technologies, by effectively embracing DT, are better prepared to compete internationally, thus achieving better export performance.
Also the Machine Learning (ML) macro-theme has been mainly analysed from the business processes perspective. In particular, some studies have tried to identify the main ML implications on DT in marketing (Miklosik and Evans, 2020) by investigating the advantages this technology can bring from this perspective (Kazaishvili and Khmiadashvili, 2020;Miklosik and Evans, 2020;Polyakov and Gordeeva, 2020;Sargut, 2019). Literature focused its attention on the social media analysis (e.g., sentiment analysis on social media); packaging; product and purchasing decisionmaking; and advertising (e.g., interactive ad placement and targeting ads). Given that ML is a subset of AI, the literature focused on ML usually underlined, from the employee and customer perspectives, advantages very similar to the AI-related ones. More in detail, from the customers' perspective, ML can offer personalized shopping experiences thanks to its ability to deeply know their preferences and interests. Conversely, from the employees' viewpoint, literature mainly highlighted the key impact of ML on knowledge building and sharing (Subramani, 2019).
Concerning the online collaborative/support platforms/systems macro-theme, it emerges how it has been equally analysed from the employee and business processes perspectives. From the employee perspective, Azeredo et al. (2020) provided a proposal for the realization of an online business consulting plan through the adoption of an online collaborative platform called LexDoBusiness. More in detail, the research aimed to analyse the acceptability of this platform, which offers several benefits, especially for what concerns the levels of cohesion and cooperation between the actors involved in the business plan. In their study, Bhatnagar and Grosse (2019) underlined the relevance of a digitalized agile workplace since it allows to make employees more productive and satisfied. Similarly, Minculete and Minculete (2019) emphasized the key role of education and training actions aimed at providing staff members with the required skills for the new technologies and systems adoption. By specifically focusing on the business processes perspective, Bruskin et al. (2017) examined the development of support systems for decision-making in terms of marketing by specifically focusing on the analysis of the business effects from the adoption of similar systems.
As regards the virtual and augmented reality, literature has mainly examined it from the customer and business processes perspectives. For what concerns the first viewpoint, the majority of studies have investigated the consumers' propensity to interact with this tool (Voronkova, 2018). Additional researches have focused their attention on the new opportunities deriving from adopting virtual and augmented reality for personalized online shopping experiences (Kim, 2020). From the business processes perspective, the virtual/augmented reality has been particularly examined with respect to the communication and advertising procedures. Notably, extant research underlined how firms can adopt the virtual reality technology to promote products and services in innovative and visual ways (Voronkova, 2018).
For what concerns the last identified macro-themes (i.e., websites/SEO; cloud infrastructure; chatbots; drones/smart robots; security protection systems; 3D print), results have already revealed a minor attention dedicated to them by the extant research (Table 5). By focusing on the websites/SEO topic, the customer and business processes perspectives represent the most investigated viewpoints. Existing studies have particularly analysed the websites topic with respect to the customer relationship management/customer connectivity/centricity (Ballestar et al., 2019) and customer experience/journey (García et al., 2019) micro-themes. With regard to the business processes perspective, the reviewed contributions have especially deepened the micro-themes of branding, communication policy, and business process efficiency. Specifically, Natorina (2020) underlined the need to implement effective marketing strategies within the DT scenario by specifically focusing on the search engine optimization (SEO). Overall, the author highlighted how the SEO represents an integral component of a successful marketing strategy since it increases the organic traffic and conversion by also enhancing the firms' attractiveness in the sight of the Internet users.
Concerning the cloud infrastructure, it has been especially analysed from the customer perspective (Ulas, 2019) by investigating its impact on consumers' preferences and behaviours. At the same time, the cloud infrastructure has also increased the human resources capabilities (Ulas, 2019) and improved the business processes. Notably, Kumar-Singh and Thirumoorthi (2019) shown that cloud-based digital infrastructures allow firms to increase agility, maximize resources, and improve services by also reducing operational costs. The authors also underlined the importance to analyse the impact of this technology from the demand side in order to examine how it can impact on customer preferences and behaviours.
As for the chatbots, these have been analysed from the business processes perspective and, to a lesser extent, from the employee one. Hence, an interesting research gap emerges with respect to the customer viewpoint. In particular, concerning the business processes perspective, Damnjanovic (2019) proposed a case study analysing the international positioning and go-to-market strategy of a chatbot solution, namely Weaver, which can be defined as an AI-based firm platform allowing to facilitate and simplify the sales processes. In the same year, the study of Sargut (2019) offered an insight related to the SMEs awareness, readiness, and capability in facing the DT challenge. Almost all the interviewed SMEs have confirmed to be interested in the DT subject and ready to implement chatbots and/or voice-operated machines in their business activities and processes.
Even if results underlined scarce attention of the recent literature on the robotics macro-theme (with the few identified contributions focused on the employee and business processes perspective), with the advent of the COVID-19 and the consequent reduction of human contacts, this topic will probably obtain, in the future, greater emphasis. Notably, robots will be increasingly adopted not only in order to substitute human resources but also to interact with customers. Indeed, robots "are expected to be progressively more autonomous, flexible, and cooperative" (Almeida et al., 2020, p. 102).
As for the last identified macro-themes (i.e., security protection systems and 3D print), while Li et al. (2020) emphasized the need to establish a new generation of security protection systems to increase the business processes efficiency, Ulas (2019) especially highlighted the key relevance of 3D printers in the process of new products development and design.
By considering the residual (but not irrelevant number of) contributions referring to the digitalization phenomenon as a broader macro-theme of analysis (i.e., digitalization phenomenon), it emerged an overall preference towards the adoption of a business processes and customer perspective. With regard to the former, two of the most investigated effects are the so-called "digital metrics" and "business process efficacy". Indeed, the digitalization phenomenon has profoundly affected the analysis of the firms' performance. Hence, the adoption of digital tools allows firms to precisely monitor and measure their social ROI (Return on Investment) in a totally new and disruptive way compared to the past. In particular, by measuring online reactions (e.g., customers' views, likes, comments, shares), the digital metrics can contribute significantly to evaluating an ad campaign in real-time, thus permitting to modify it accordingly (e.g., Bughin et al., 2019). Moreover, a number of contributions focused on the business processes perspective has specifically analysed the role played by the digital tools in increasing the quality of the firms' processes, thus elevating their levels of operational and organizational excellence (e.g., Kuimov et al., 2019). On the other hand, from the customer perspective, literature has mainly investigated the impact of the digitalization phenomenon on the customer journey (e.g., Taylor et al., 2020) and on the relationship management between firms and customers (e.g., Barann, 2018).
After the content analysis process has been concluded, Appendix 2 has been created, displaying the classification of the articles based on the following categorizations: (i) Author/s; (ii) Title; (iii) Source; (iv) Year of publication; (v) Analysed macro-theme; (vi) Analysed micro-theme with (vii) The respective analysis perspective (i.e., EP, CP, BPP).

General discussion
Both the descriptive and thematic results of this study provide interesting insights into the analysis of the DT-marketing topic, while crafting new propositions for future research agenda.
Descriptive data highlight the growing focus of the literature on the digital transformation-marketing topic over the last few years, with the majority of contributions published between 2019 and 2020. Notably, only nine publications have been found in the four-year period 2014-2017, while thirteen publications were reviewed in 2018, forty-five in 2019, and fifty in 2020. The publication sources are highly fragmented, given that ninety-three sources have published the 117 reviewed papers. The more cited contributions-besides being published between 2019 and 2020-have especially focused on the impact of the digitalization phenomenon on (i) Customer relationship management (Ballestar et al., 2019;Gil-Gomez et al., 2020;Hausberg et al., 2019;Peter et al., 2020;Sivarajah et al., 2020), (ii) Its coexistence with the human resources (Almeida et al., 2020;Gil-Gomez et al., 2020;Ulas, 2019;Yigitcanlar et al., 2020), and (iii) The improvement of the business processes' performance (Sestino et al., 2020) by specifically focusing on market knowledge (Hausberg et al., 2019), communication (Ballestar et al., 2019), product development (Ulas, 2019), and sales activities (Almeida et al., 2020). Moreover, the majority of contributions here analysed has employed qualitative methods. Overall, these data, while suggesting an increasing interest by the scientific community towards the DT-marketing phenomenon, depict the absence of sources systematically and continuously dealing with this field of study, a dominant focus on certain issues, and the need to improve the adoption of quantitative methods in future research, both to validate previous research findings and to make them more generalizable.
Concerning the research questions guiding this study and, in particular the analysed themes (RQ1), these can be grouped on a twofold level concerning (i) The study of digital technologies employed in the field of marketing (macrothemes), and (ii) The impact of such technologies on specific marketing activities (micro-themes). Overall, the literature analysis suggests an increasing pervasiveness of digital technologies in the marketing field. The use of such technologies, in fact, affects the consumer behaviour, as well as the way marketers work and marketing activities are managed and organized. In particular, it is worthy to note that DT involves the most operational marketing activities (e.g., Caliskan et al., 2020), such as sales (e.g., Almeida et al., 2020) and communication policies (e.g., Alassani and Göretz, 2019;Dasser, 2019), allowing a general increase in these processes' quality. Meanwhile, DT also affects the analytic and strategic areas of marketing, improving the opportunities to reach new groups of consumers through the systematic use of digital technologies (such as Big Data) that allow a deeper segmentation of the market (e.g., Almaslamani et al., 2020). It supports the development of new branding strategies and the increasing visibility of brands, thanks to the use of online and social channels (e.g., Kazaishvili and Khmiadashvili, 2020;Melović et al., 2020). Moreover, DT impacts on companies' innovativeness, helping the implementation of more effective and efficient innovative processes (Calle et al., 2020), and changes the overall relationships between firms and consumers by encouraging a customer-centric organizational culture (Cherviakova andCherviakova, 2018, Graf et al., 2019) and the customer participation in the value creation process (Hughes and Vafeas, 2019). According to Dasser (2019), DT also implies a deeper change of marketing by elevating its strategic role as a catalytic accelerator in the digital business transformation journey.
These studies are driven by different perspectives of analysis (RQ2). The majority of research considered in this review employed a business process perspective by examining how digital technologies impact on specific marketing processes, such as sales and communication management. Nevertheless, by focusing on the main investigated topics, findings reveal that the existing research has been principally guided by a customer perspective, i.e. the way in which digital technologies are transforming customers' behaviour, experience, and relationship with companies, followed by the business processes perspective concerning the investigation of potential improvements occurring in the area of marketing analysis and control. The employees' perspective emerges as the less relevant among the others, despite it includes a critical part of the literature focused on the relationship between DT and human resources management. More in detail, as it emerged from our dataset, the employees' perspective mainly characterized the first publications, investigating how digital technologies are enhancing (and requiring) the development of new marketing and business skills dealing with DT (Kwon and Park, 2017;Van Belleghem, 2015). Over the time, the scientific attention has been moved increasingly towards the customer and business processes' perspectives. Most of the contributions published in 2020, indeed, dealt with the analysis of the DT phenomenon from the consumer viewpoint, specifically investigating the management of the customer-firm relationship (e.g., Gil-Gomez et al., 2020;Sivarajah et al., 2020), and from the business processes' viewpoint, especially analysing the key relevance of the digital tools in measuring the firms' performance in the social sphere (e.g., Al-Azani and El-Alfy, 2020; Lin et al., 2020). Probably, this growing interest of the research derives from the advent and unleashing, during 2020, of the COVID-19 health crisis that has led companies to almost completely digitize the relationship with customers due to the limitations imposed by the anti-COVID-19 decrees.
All these findings provide several contributions both theoretically and practically.

Theoretical implications and research gaps
From a theoretical standpoint, this is the first study that offers a systematic and thematic review of the existing literature on DT and Marketing, while previous reviews, in the marketing field, have been very narrow in perspective. Hofacker et al. (2020), for example, examined the relevant literature on digital marketing and B2B relationships, while Miklosik and Evans (2020) focused on the impact of big data and machine learning on marketing activities. Our review, instead, addresses the DT-Marketing binomial from a wider and more comprehensive perspective, including all prior research dealing with DT in the marketing area. By doing so, this study outruns the scope of prior reviews that have been often limited to certain domains, and provides a comprehensive framework that offers a synergistic view of the existing literature, which allows a more inclusive vision and understanding about the phenomenon. By doing so, this review also permits to highlight some relevant research gaps on which future studies might focus on.
From the combined overview between macro-and micro-themes, the main research gaps relate to the necessity of deepening the analysis of the impact of specific macro-themes from the employee (i.e., social media channels, big data, mobile marketing, Artificial Intelligence, Industry 4.0, Cloud infrastructure, Virtual/augmented reality, and websites), customer (i.e., Social media channels, Big Data, Industry 4.0; Internet of Things; Machine Learning; Websites; Chatbots), and business processes perspective (i.e., Mobile technology; Artificial Intelligence; Virtual/ Augmented reality; Cloud infrastructure; Drones/Smart robots).
Besides that, the variety of analysed studies, while manifesting the pervasive use of digital technologies in the marketing field, reveals that the extant literature is quite fragmented and even sparse with regard to specific micro-themes. Some topics, like customer service, smart factories, consumer behaviour, have been investigated by few contributions, thus highlighting potential opportunities for further studies. In Fig. 3 Areas of future research on DT and Marketing this respect, our review can be viewed as a solid basis for additional discussion and research within each perspective emerged from the analysis (see Fig. 3).
More in detail, the findings reveal that the employees' perspective is worthy of further attention, as it is the less investigated one. Although several contributions (n. 21) focused on DT and human resources by highlighting the need for enhanced skills in using technology (e.g., Dethine et al., 2020;Ulas, 2019), the development of new prominent job positions for the future (e.g. digital marketing manager; social media manager; big data/data analyst) (e.g., Di Gregorio et al., 2019, Hafezieh andPollock, 2018), and the critical role of training and educational actions enhancing the appropriate use of digital technologies in the marketing context (Yigitcanlar et al., 2020), other themes have been under-investigated. In particular, only two papers dealt with the subject of smart technologies by investigating how they can help cities to face the increasing urbanization (Visan and Ciurea, 2020), and their importance for establishing a predictive maintenance of production systems, which can increase the process quality (Chehri and Jeon, 2019). The application of smart technologies can also redefine the way people conduct business, bringing benefits in terms of productivity and employee well-being (Papagiannidis and Marikyan, 2020). Thus, there is scope for considering, in future research, how smart technologies are used to conduct marketing activities and how they are changing the way marketers work and organize their processes.
Under the customer perspective, several topics might deserve attention in future research. Most of the analysed contributions addressed the impact of DT on firms/ customers relationships, highlighting the need for new forms of interaction and collaborations with customers due to changes in behaviour. Several scholars recognized the advantage of DT as it allows to establish innovative and real-time relationships with the market (e.g. Almaslamani et al., 2020), to engage customers in the value creation process (e.g. Saravanabhavan et al., 2020;Taylor et al., 2020), and to provide customers with more interactive and personalized experiences (e.g. Taylor et al., 2020;Venermo et al., 2020). However, our findings suggest that other topics, although relevant, are still at the begin of their investigation. Only three contributions focused on customer service (Lieberman, 2019;Lin et al., 2020;Safiullin et al., 2020), especially revealing the role of digital tools in the online customer service and the importance of electronic services for improving customer satisfaction (Lin et al., 2020). A recent study (Galvani and Bocconcelli, 2021) revealed that a new business model is emerging in the BtoB context characterized by an overall revolution towards the digital servitization strategy, which replaces the traditional product-centric paradigm. Hence, future research could investigate whether and how the digital servitization strategy is currently implemented in the BtoC context, which opportunities and benefits can offer-especially concerning the firm-customers' relationship, and how marketing managers can act to face the imperative complexity linked to its adoption. Another theme receiving increasing-but still few-attention concerns the buying/consumption processes. Few scholars analysed the impact of digital tools on customers buying processes (Kim, 2020), the increasing use of e-commerce (Cahyadi, 2020), and structural changes occurring in consumption during COVID-19 pandemic (Kim, 2020). However, the identification of consumption patterns and trends has been always a central topic in the marketing literature, as proved by the wide number of literature reviews, even focused on specific areas such as electronic word of mouth (Huete-Alcocer, 2017), online consumption (Hwang and Jeong, 2016), or COVID-19 crisis (Cruz-Cárdenas et al., 2021). Therefore, continuing the research on DT and consumption/buying behaviour is desirable to properly adapt the marketing management with the aim of satisfying specific market needs and expectations, as well as realizing a stronger engagement of customers in the value creation process, which is getting more and more attention within the recent marketing and management literature (Fan and Luo, 2020). Besides, future studies on DT and consumption/buying behaviour might also employ modern research methods, such as neuromarketing. We found only one contribution based on the analysis of the use of advanced methods in the field of artificial neural networks (Polyakov and Gordeeva, 2020). However, neuromarketing could contribute to overcome several limitations associated with traditional data collection method (i.e. self-report data), while allowing to capture unconscious brain processes that relate to consumer decision-making (Sung et al., 2021).
Finally, an additional space for future research emerged from our review of publications is related to the business processes perspective. This area shows the greatest potential for exploration, given the richness of themes it includes. In this perspective, in fact, except for some activities related to marketing analysis and control, and operational policies-especially product and communication ones-the rest of the literature appears very fragmented and scarce. Notably, specific attention might be devoted to DT and export process management, as Naglič et al. (2020) found that firms which invest in DT are better prepared to compete internationally and achieve better export performance; branding strategies, as they have been recognized as critical for marketing competitiveness (Kazaishvili and Khmiadashvili, 2020), drivers/ barriers and risks associated to DT implementation in the marketing areas; and sustainable/social opportunities and treats that digital technologies can bring with them, as they can differently affect the success of human-centric marketing programs in the digital environment (Agafonova et al., 2020). All these topics have been very little investigated by previous research, while deserving increasing attention given their relation with companies' success and long-term competitiveness.

Practical implications
Regarding the practical contributions, our review offers a number of suggestions to marketing managers as it analyses the DT-Marketing binomial both internally (i.e. on the firm level) and externally (i.e. on the inter-firm level). This approach results from the recognition of different perspectives of analysis adopted by prior research, which combines contributions focused on the management of internal processes and marketing activities with studies investigating the DT phenomenon from a customerbased viewpoint. Consistent with our twofold approach of analysis, the practical implications deserving particular attention can be summarized into two main groups concerning (i) The changing role of marketing in the company resulting from the increasing use of digital technologies, and (ii) The changing relationships between firms (and marketing) and external stakeholders (especially consumers).
Literature suggests that DT could improve the strategic role of marketing within the firm, as it enhances the marketing capability to analyse the market scenario and to develop a more comprehensive understanding of the demand (Papagiannopoulos and Lopez, 2018), which, in turn, can support new products development that are better aligned with customers' expectations (Kuimov et al., 2019). Overall, digital technologies can help companies to become data-driven subjects, where marketing covers a central position given its informative and intra-firm coordinating role. However, the full exploitation of such opportunities means change, at both cultural and structural levels. Our review, in particular, reveals that DT requires a cultural upgrading, to cope with DT and its effects on the business (e.g., Álvarez-Flores et al., 2018;Dethine et al., 2020), the enhancement of internal competences in the field of technology (Ulas, 2019), the development of new job positions (Di Gregorio et al., 2019), and the gradual adoption of new working habits and patterns (Minculete and Minculete, 2019). Of course, educational and training activities become prominent to support such changes, passing through the acquisition of new skills from the market labour, as well as through the enhancement and conversion of internal resources. Besides training programs, organized both internally and externally in collaboration with private and public institutions such as high schools and universities, companies could also provide ad hoc rewards to encourage the commitment and interest of marketing employees in digital innovation.
The second group of advices concerns the changing relationships between firms (and marketing) and external stakeholders (especially consumers). DT affects the customer behaviour and changes his ability to communicate with the company (e.g., Caliskan et al., 2020), to be engaged in the value creation process (e.g., Taylor et al., 2020), and to live personalized consumption experiences (e.g., Fokina and Barinov, 2019). All this implies a general re-thinking about the firm-customer relationship management. Consumers are becoming empowered subjects that no longer accept the role of passive receivers of marketing initiatives (Acar and Puntoni, 2016) and companies need to open to their customers, accepting their participation in the marketing decision-processes. Undoubtedly, the use of social-media platforms can be decisive to create engaging content and connect with customers, improving the interaction and the dialog with them, for example by responding to a specific comment or complaint (Acar and Puntoni, 2016). However, digital technologies can be also used to create more advanced tools that are able to strengthen the connection between brands and customers, such as crowdsourcing, co-creation, and/or brand communities. These platforms can be used successfully by firms to improve the dialog with customers and their involvement in several marketing processes, such as the selection of an advertising campaign and/or the creation of new product ideas.

Conclusions and limitations
This study provides a synergistic view of existing literature on the binomial DT-Marketing by detecting the main themes investigated and the relative approach of analysis characterizing prior research. It offers a comprehensive framework, which combines both internal and external perspectives to analyse the impact of DT on all the activities on which the traditional marketing management is based, dealing with the areas of market information and knowledge, marketing strategies, and operational policies. Moreover, it also considers how the binomial DT-Marketing has been investigated in the wider context of the firm, by taking into account the organizational, human, and structural changes associated to the adoption of digital tools in the marketing field. By doing so, our review synthetizes prior research on DT and marketing, provides suggestions for future research directions, and offers practical implications for marketing managers. Notwithstanding these contributions, the current study presents its limitations.
First, despite the adoption of a rigorous methodological approach in conducting the review, some pertinent studies are likely to have been omitted, as the research was based on a certain combination of keywords in the search string and, above all, it was focused on a single database, i.e. Scopus. While Scopus covers all top journals and scientific publications, containing most references from other databases (Guerrero et al., 2015), it could not necessarily capture all contributions due to retrieval conditions and data source limitations. Therefore, a future updating of the current review should consider other leading databases, such as ISI, Web of Science, and EBSCO, which are also appreciated for their comprehensiveness in the field of peerreview literature and management research (Schryen, 2015).
Second, the analysis was focused on recent literature published between 2014 and 2020. Although the literature on DT has gained in interests over the last years, especially from 2014 (Vaska et al., 2021), there may be articles and authors that do not come under our review. Moreover, the results are valid only for the specific timeperiod we considered in this study. Therefore, a future review (e.g., including the years before 2014 and the years after 2020) might extend the time framing as new research works could modify our findings, particularly in light of the constant development of digital technologies and marketing scenarios.
Finally, in our review, the qualitative analysis and descriptions are based on the research team interpretation of the selected references, which is subject to the limitations of human judgments. While it is impossible to eliminate human interpretation in scientific research, as it is critical to make the results more meaningful (Zhu et al., 2021), a future review could combine bibliometric analysis methods (e.g., citation, main path analysis) with subjective analysis, to reduce the influence of human interpretation and provide a more accurate description of DT-Marketing research. To this end, the use of appropriate software tools, such as VOSviewer, should provide notable improvements to the research quality, as it allows to create large bibliometric maps, which offer a clear and easy way to manage the visualization of data analysis (Shah et al., 2020).

Appendix 1
See Table 10.  (Melović et al .,p. 4); [2] "Social media marketing is used across sectors and refers to "the utilization of social media technologies, channels, and software to create, communicate, deliver, and exchange offerings that have value for an organization's stakeholders" (Melović et al .,p. 4); [3] "Social media is a communications and networking tool whose popularity has been constantly rising since its users can connect, share, and interact among themselves" (Melović et al.,; Social media can be defined as "a pertinent platform for public engagement, inter-organizational relationships, and public information" (Sivarajah et al., 2020, p. 165 (Sestino et al., 2020, p. 1); [2] Big Data is the term that can be used to refer to this extremely broad set of data, which, therefore, needs special tools to store, extract, organize, and transform the data into information that can be analyzed widely and in a short time (Almeida et al., 2020, p. 100); [3] Big Data is an evolving term that is used to describe any large amount of structured, semi-structured or unstructured data that has a potential to be mined for information (Ulas, 2019, p. 665) Mobile marketing (Mobile technology; Smart apps) [1] Digital mobile application can be a new business model in selling products from companies (Cahyadi, 2020, p. 3); [2] Mobile marketing "can be defined as the planning and execution of all mobile-based marketing activities that influence a shopper, from the initial shopping trigger, to the purchase, consumption and recommendation stages" (Kaczorowska-Spychalska, 2018, p. 15) The IoT can be seen as the network of physical objects that contains technologies and software that enables them to communicate and interact intelligently internally or with their external environment over the Internet" (Almeida et al., 2020, p. 100); [2] "Whereas the term "Internet" refers to a virtual network-oriented vision of technology, the term "Things" emphasizes the objects that can be integrated into a technological framework" (Sestino et al., 2020, p. 2); [3] "IoT is meant as an information infrastructure around the world where unique physical and virtual images have been identified and linked to the internet which have sparked innovative, sophisticated services, and created a simpler and smarter life" (Hamidi et al., 2020(Hamidi et al., , p. 1540; [4] "Internet of things is a technology based on data transfer between devices over internet. It consists of interconnected devices from simple sensors to smartphones and wearable devices" (Ulas, 2019, p. 664) Artificial Intelligence [1] "AI can be defined as machines or computers that mimic cognitive functions that humans associate with the human mind, such as learning and problem solving. AI is a branch of computer science that perceives its environment and acts to maximize its chances of success" (Yigitcanlar et al., 2020, p. 3); [2] "Artificial intelligence investigates how a human brain thinks and how people learn and decide as they try to solve a problem, and it imitates the results of this study with smart software. Artificial intelligence does not act upon programmer's mind, it learns, understands and judges itself" (Ulas, 2019, p. 664) Italian Journal of Marketing (2023) 2023:207-288 The main difference of Industry 4.0 from the other industrial revolutions is to connect people, machines, and objects to improve the efficiency of production while involving the customers to all processes" (Caliskan et al., 2020(Caliskan et al., , p. 1252; [2] "It concerns a shift in the production practice-from mass to personalised production-which results in greater flexibility of production processes and provides means to satisfy the individual needs of different customers more effectively" (Nosalska and Mazurek, 2019, p. 10); [3] The main principles of marketing for the Fourth Industrial Revolution are: Cooperation, Conversation, co-creation, cognitivity, connectivity" (Nosalska and Mazurek, 2019); [4] "Industry 4.0 involved digital transformation that describe the future of industry" (Hamidi et al., 2020(Hamidi et al., , p. 1540[5] "In fourth industrial revolution, it is foreseen that manufacturing process is digitized, machines are directly connected to each other and personalized manufacturing is possible, besides that, environment is less polluted as a result of productivity growth, avoiding of excessive use of energy and water sources. As manufacturing becomes flexible with digital factories, manufacturing meeting less and personal product demand becomes possible" (Ulas, 2019, p. 664) Machine Learning [1] Machine learning (ML) is strictly connected to the computer science domain. It allows personal computers to become more efficient, in a specific task, through experience. ML can be applied, in the marketing domain, in the social media analysis, product and purchasing decision-making, and advertising (Miklosik and Evans, 2020) Online collaborative/ support platforms/systems [1] Online collaborative systems are platforms providing several benefits, especially for what concerns the levels of cohesion and cooperation between the actors involved (Azeredo et al., 2020) Virtual/ Augmented Reality [1] "Augmented reality (AR) is described as the extension of physical reality by adding layers of computer generated information to the real environment. Information in this context could be any kind of virtual object or content, including text, graphics, video, sound, haptic feedback" (Ulas, 2019, p. 665) Websites/SEO [1] "Digital transformation and the high level of offline and online competition have a significant impact on business, which emphasizes the relevance and need to implement the successful relevant marketing strategy that includes the search engine optimization (SEO). The SEO increases the business visibility on the Internet in comparison with priority competitors, promotes better communication and interaction in accordance with varied requests of online buyers (customers, clients)" (Natorina, 2020, p. 83);

Appendix 2
See Table 11. Macro-themes Definitions extracted from the reviewed contributions focused on the marketing domain Cloud Infrastructure "It is a general term of internet based information services providing computer sources which are used or shared between users on request for computers and other devices" (Ulas, 2019, p. 665) Chatbot's [1] "Chatbots are an innovative way of interacting with customers and they are well-known for their advantages such as: availability, handling capacity, cost efficiency and personalization. They are present wherever the customers are, responding to requests immediately. A chatbot is an instant messaging account that able to provide services using instant messaging frameworks with the aim of providing conversational services to users in an efficient manner" (Damnjanovic, 2019, p. 40); [2] "They are software applications which are designated with the intent of backing up users in service sectors and imitate written or verbal human speaking" (Ulas, 2019, p. 665) Drones/Smart Robots "Vehicles with reduced or no human intervention. Robotics shift the labour/capital mix while managing societal expectations" (Ulas, 2019, p. 666) Security Protection systems The security protection systems concern the following boundary types: Information Intranet and Third Party Boundary; Information internal and external network boundary; Security Boundary between Horizontal Domains of Information Intranet, and Vertical Security Boundary of Information Intranet. The main security protection technologies are: Hardware Firewall or Software Firewall; Virtual Firewall Technology; Access Control Technology between VLANs (Virtual Local Area Network)  3D Print "It is a device quickly producing models which are designed in computer or prepared in 3D by using various materials without any mould or fixture" (Ulas, 2019, p. 665) Italian Journal of Marketing (2023) 2023:207-288