**2. Literature Review**

In this section, a literature review of the studies on the relationship between e-skills and e-activities is presented. For its measurement, some tools and tests were used, such as correlation matrix, benchmarking analysis, and Excel data analysis. Due to globalization and new technologies, all processes, including communication, are changing and organizations are using flexible networks to communicate [13] (p 1). The world is becoming smaller and inter-related using the Internet to create trust and facilitate working in teams [14] (p 257), as well as making information available to anybody at any moment [15] (p 171). In terms of technology, we live in a golden age of communication. Global communication has been helped by the Internet, e-mails, faxes, mobile phones, and text messaging, as well as the mediated communication through Internet, e-mail, and mobile phones [16] (p 67). According to the official statistics, the number of Internet users increased from 360 million in 2000 to 4.5 billion in 2019 [17], and the number of websites increased from 17 million in 2000 to 1.5 billion in 2019 [18].

This exponential development has mainly been due to the constraints created by globalization. No one, nor physical persons or juridical ones, cannot allow for a "technological fracture", because this will mean the exclusion from the regional (European) market which actually became a global one [19] (p 30). In the past few years, there has been a growth in Internet markets [20] (p 15). According to the principle, healthy people in healthy organizations, producing healthy products for healthy customers, human resource plays an important role in the application of the sustainable development activities by developing its e-skills.

Efficiency in organizations is achieved by their human resources, their behavior, knowledge, and skills, as well as sustainable development. Sustainability of an organization is achieved by the skills of the employees, leadership, and managers in deploying activities. In a world where the resources are limited, accepting sustainability supposes the responsibility towards future generations. The learning of the continuous development of the human capital must also become sustainable, allowing organizations to compete in a changing market which is economically and socially responsible. First, sustainable processes must be aligned with the business model, used by all departments, and understood by all employees.

The Internet has become the universal source of information for millions of people, at home, at school, and at work [21]. In 2005, on average 27.3%, and in 2019, 49.7% of the households in the EU had a personal computer at home; whereas, in 2004, 42%, and in 2018, 89% had a home Internet connection. The penetration of computers and especially of the Internet remains lower in thinly populated, rural areas throughout the European Union [22].

Communication has contributed to the global connection of society through the Internet. Men and women, and especially the new generation, are online almost all of the time [23] (p.1). Internet, especially e-communication, provides the opportunity to exchange ideas and information at the global level [24] (p 43). The Internet will become the most convenient tool of global communication worldwide [25] (p 10), enabling even small businesses cross many internal barriers [26] (p 20) and enter to the global market. Due to exceptional online experience [27] (p.2), from 2002, Internet traffic has increased by 86 percent a year, and from 1995, websites have increased from 20,000 sites to over 36 million by 2002 [14] (p 68), and by 2020, to 1.7 billion websites [18].

The Internet is not just about connecting people, it is about attracting customers, offering them independent choise, diversity, transparency [28] (p.45), convenience or flexibility [29], and maintaining and growing relationships with stakeholders. In North America, 88.1% (2018) and 89.4% (2019) use the Internet, while 77.4% (2018) and 87.7% (2019) from the European population and 47.7% (2018) and 58.8% (2019) worldwide use the Internet [30], and employees use e-mails every day (with 269 billion e-mails sent every day in 2017 and 306 billion e-mails sent in 2019 [31], however, e-communication is not yet a substitute for face-to-face communication, but a new means to communicate faster and cost effectively.

The Internet reduces face-to-face meetings with clients, creating psychological barriers and physical distance; but modeling, used in many fields, and in our case in e-activities, will bring benefits for companies and for customers, being a paramount to economic policy [32]. In addition to this type of communication, managers use e-mails, intranet, videoconferencing, or enterprises' software to communicate with their employees [33] (p 165). IBM, for example, offers more than 5000 audio and video podcast "episodes" for employees to watch or listen whenever they have time.
