An introduction to instructional technology systems used for distance learning applications is provided, with a compilation of technical information in straightforward terms. Broadcast communications theory is discussed, and several models of communications are considered, including transport mechanics and network facilities. The most prevalent feature of the technology applications associated with distance learning is teleconferencing. The four primary modes of teleconferencing are audioconferences, audiographic teleconferences, computer conferences, and video teleconferences. Interactive distance learning technologies are categorized as narrow-band or broadband systems, both of which are described. The distinctions between analog and digital transmission are identified. Nontechnical users of distance learning systems will benefit from the rudimentary information in this paper. Five charts illustrate models and means of distance education. (Contains seven references.) (SLD)