During an important fraction of 19th and 20th centuries distance learning was a supporting tool for starting education, post graduation, or professional training to those who lived in peripheral areas. Therefore, Holmberg (2005) identifies several generations of distance learning:
1st generation (1840 to 1970)- acknowledged correspondence courses;
2nd generation (1970 to 1980)- open universities era, in which universities have full degree programmes through new media, in a systematic way, and having evaluation systems in various parts of the world;
3rd generation (1980 to 1990)- videotapes and TV were the key technological features;
4th generation (from the “90s” until now)- online teaching/e-learning are learning enablers. Nevertheless, this generation encompasses various strands (see section online learning generations).
Despite each generation technological features a common characteristic arises: until the 21st century presence and distance learning prevailed in two dissimilar worlds (Holmberg, 2005). Although, the evolution of e-learning to blended learning due to technological evolution gathered both realities. As a result, a distinctive feature of knowledge society is content massive production and distribution in multiple forms in order to support lifelong learning in all learning environments (Commission of the European Communities, 2009; Tuomi, 2004). Therefore, Harris, Connolly & Feeney (2009) argue that for a successful learning process in nowadays blended learning is crucial. This resumes online learning features (content delivery, potential, aperture and versatility), as well as presence learning (formal contact), in spite of e-learning latest streams of the fourth generation allow purely e-learning, as well as learners’ characteristics.