Teletext systems transmit news and information to subscribers, either superimposed over the television picture or on separate, full-screen pages. To receive teletext information, the receiving television requires either a built-in or add-on decoder. The viewer typically accesses the information via a remote-control keypad. Teletext is distinguished from videotex in that it is essentially a one-way system, while videotex offers greater interactivity.

     By modern computer standards, teletext is a low­ resolution medium. A broadcast signal can transmit up to 200 user-selectable pages. When a user selects a page, it can take up to 20 seconds to load. Each page is limited to seven colors, plus black and white, and can hold up to 24 rows of 40 characters. This means that a one-screen news story is limited to about 80 words.

     In the 1970s and early 1980s there was substantial development in creating teletext technology and programming. In the United Kingdom, the British Broadcasting Corporation (BBC) began its CEEFAX service in 1974. The IBA instituted its ORACLE system in 1975. While teletext achieved high levels of awareness in the U.K., it reached small audiences compared to the television viewing audience; its most common (and still continuing) use there is to provide subtitles for the hearing-impaired.

     Canada's TELIDON system featured a vector-based graphic system that permitted more advanced graphics to be loaded in the low-bandwidth medium. This technology became part of the NABTS protocol that became most popular in the United States, where the Federal Communications Commission (FCC) authorized teletext service in 1983. The FCC declined to set a technical standard for teletext, opening the door for many incompatible systems. In the US there were also many different business models for teletext. An early version, KEYFAX, was transmitted via satellite on superstation WTBS beginning in 1982, and cost $19.90 per month, including rental of the decoder. This system survived for two years, when it was abandoned for a videotex service. Other systems required the viewer to purchase a decoder for up to $300. Some were created to be advertiser-supported or were designed to appeal to narrow audiences, such as classified ads or financial information.

By 1985, teletext was in decline in the United States. It was hampered by availability and price of decoders, lack of technical standards, increased interest in videotex, poor-quality graphics, limited information, and no clear business model. Videotex systems that followed also struggled, until the Internet gained the necessary critical mass to deliver the kinds of services the pioneers of teletext systems had dreamed of and hoped to provide.