This overview of videotex covers three types of systems--teletext, viewdata, and cabletext. Teletext, which stores information as a series of pages which are broadcast along with television pictures for viewing on specially adapted television screens, is characterized as journalistic, and the offerings of three British systems--CEEFAX (BBC), ORACLE (ITV), and 4-TEL (C4)--are described. The offerings of viewdata, best known in the United Kingdom as PRESTEL, are also described, with emphasis on the interactive nature of the technology. Applications of viewdata, which uses telephone lines and modems to deliver information, are also briefly described, including electronic mail and bulletin boards, a gateway system for linking user terminals, and teletransactions such as banking and shopping. The costs of both teletext and viewdata are discussed. A brief description of cabletext, a hybrid technology which is not yet fully developed, focuses on its potential impact on other videotext systems. Discussions of the educational role of videotex cover three types of applications: as suppliers of information, as components in teaching about information technology, and as microviewdata and teletext emulation software for DIY ("do-it-yourself") videotex running on a stand-alone microcomputer. A glossary and a 19-item reading list are provided. (DJR)