ORACLE was a commercial teletext service first broadcast on the ITV network in 1978 and later additionally on Channel 4 in the United Kingdom from 1982. The service ceased on both channels at 23:59 UTC on 31 December 1992, when it was replaced by Teletext Ltd.

Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval area at the top and bottom of the screen. The teletext decoder in the television buffers this information as a series of "pages", each given a number. The user can display chosen pages using their remote control. In broad terms, it can be considered as Videotex, a system for the delivery of information to a user in a computer-like format, typically displayed on a television or a dumb terminal, but that designation is usually reserved for systems that provide bi-directional communication, such as Prestel or Minitel.