Teletext is the term commonly applied to electronic systems that transmit to specially equipped television receivers. This technology makes use of normal broadcast signals to distribute data to television sets or dedicated monitors. The data is provided in the form of "pages" made up of screens of colorful text and graphic information. The broadcasted data may contain information such as news headlines, sports scores, and traffic and financial reports.

Although the signals may sometimes be transmitted as a subcarrier on an FM radio signal, teletext systems usually transmit digital data by placing messages in the unused lines of the standard television signal. These unused lines are called the Vertical Blanking Interval or VBI: this can be seen as the black bar that appears when the vertical hold is defective on a television set. A special decoder is required to retrieve and display the text and graphic content: this decoder may be built into a television set or cable decoder or it may be installed as a peripheral device. The teletext information may be displayed in a superimposed format or full screen image, or it may be relegated to the lower part of the video display. Viewers are able to control the display of this information with a handheld remote control device. In some systems special printers may be connected to the sets which are able to reproduce provide hard copies of the broadcasted data.

In contrast to videotext services which are fully interactive, teletext has traditionally has been a one way system. Because of the limitations of the broadcast signal, the user must access the information in order, page by page, as the station chooses to transmit it.

Teletext services have operated quite successfully in European markets since the late 1970s. In Great Britain, for example, several million sets have been equipped with decoders that allow users access to Ceefax, the British Broadcasting Corporation's teletext service, and to Oracle, a teletext service provided by Independent TV. However, teletext has had little success in the United States, in part because the Federal Communications Commission chose not to designate a national standard for teletext decoder devices. The resulting proliferation of incompatible equipment created confusion in the marketplace which ultimately contributed to the low adoption of teletext among U.S. television owners.

-Aviva Rosenstein