## 4 Materials and Methods  
Systematic reviews to synthesize existing knowledge in a discipline or on a subject are very adequate to facilitate decision-making, so they are increasingly used [36]. Scoping review is a type of systematic review that is revealed as a useful methodology for providing actionable and relevant evidence efficiently when time or cost factors are important [37]. Scoping reviews respect the key principles of systematic reviews, including the clear statement of the objectives of the review, the pre-definition of eligibility criteria, the assessment of the validity of results and the systematic presentation of results [38], with the exception that processes are accelerated and optimized. In situations where urgent decisions are required, governments, stakeholders in the health system, international organizations and civil society request rapid reviews [39]. Additionally, the scoping review questions are useful to bring together evidence from heterogeneous sources and knowledge areas [40]. For these reasons, the publication of this kind of report has become commonplace in a wide variety of areas in recent years [41]. For example, Communication Studies has participated in this actual research trend, with 70 revisions on communication issues since 2015 until June 2020, according to the Scopus database. These revisions are rigorous and explicit in the method and, therefore, systematic, but they make concessions to the breadth or depth of the review process by limiting some aspects. Several valid techniques are used in order to achieve this, such as shortening the study time, carefully focusing the question, using less sophisticated searching strategies, restricting the amount of grey literature, or extracting only key variables [42]. Consequently, they involve fewer stakeholders, fewer discussions, fewer iterations, and greater use of the previous lessons learned [43]. The preparation of such reviews is an important challenge, due to the difficulty of responding in the short term, with scientific rigor and with a standard of transparency acceptable to everything concerned, although these difficulties do not undermine their validity [44]. According to the recommendations of [PERSON] et al. [45], this research on the rural digital divide is characterized by the transparency of the method followed and the clarity of its purpose. The review was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses PRISMA protocol [46]. PRISMA was developed by a group of experts who identified the minimum criteria for systematic reviews for high-quality scientific publications. A PRISMA checklist is available to increase its transparency [47], which has been used to facilitate traceability of the entire process followed in general and the flow of information in particular. Once the research topic was defined, a four-stage process was followed: identification of relevant studies, selection of studies, mapping of data, and synthesis and reporting of the results. The final product is a narrative presentation, with minimal statistical data, that provides information to contribute to the research, practice and policy, and which, in addition to the intrinsic value that this has in itself, can serve as a starting point for future researches [48]. The inclusion and exclusion criteria were specified and documented, as described in Table 1. It was decided to use research papers published in academic journals or in proceedings of scientific conferences between 2016 and 2020 in English, French or Spanish. Monographs and chapters edited in collective books were excluded because their diffusion and impact factor are much minor. The official literature, status reports and opinion pieces in magazines were not considered because our purpose was to identify and analyze proposals based on scientific studies. On 15 June 2020, an exhaustive search was carried out on the following bibliographical reference databases: Scopus, Web of Science, ProQuest, GoogleScholar, InDICEs CSIC and Caim.