The document discusses the history and concepts of technology-enhanced learning (TEL). It notes that TEL began in the 1920s with B.F. Skinner's teaching machines. In the 1950s and 1960s, Skinner developed the theory of programmed instruction which was implemented using teaching machines and computers. The document outlines several key developments in e-learning from the 1960s onward, including the use of computers to deliver course content and early online distance learning programs. It describes different aspects of characterizing and defining e-learning approaches.