Asynchronous learning is a general term used to describe forms of education, instruction, and learning that do not occur in the same place or at the same time. It uses resources that facilitate information sharing outside the constraints of time and place among a network of people. In many instances, well-constructed asynchronous learning is based on constructivist theory, a student-centered approach that emphasizes the importance of peer-to-peer interactions. This approach combines self-study with asynchronous interactions to promote learning, and it can be used to facilitate learning in traditional on-campus education, distance education, and continuing education. This combined network of learners and the electronic network in which they communicate are referred to as an asynchronous learning network.
Online learning resources that can be used to support asynchronous learning include email, electronic mailing lists, threaded conferencing systems, online discussion boards, wikis, and blogs. Course management systems have been developed to support online interaction, allowing users to organize discussions, post and reply to messages, and upload and access multimedia. These asynchronous forms of communication are sometimes supplemented with synchronous components, including text and voice chat, telephone conversations, videoconferencing, and even meetings in virtual spaces such as Second Life, where discussions can be facilitated among groups of students.
The roots of asynchronous learning are in the end of the 19th century, when formalized correspondence education (or distance learning) first took advantage of the postal system to bring physically remote learners into the educational fold. The 1920s and 1930s saw the introduction of recorded audio, desynchronizing broadcasting and revolutionizing the mass dissemination of information. The first significant distribution of standardized educational content took place during World War II; the branches of the US military produced hundreds of training films, with screenings numbering in the millions.