Teletext is a technology that allows text and simple graphics to be transmitted over a television signal. It was primarily used for delivering news and information, but it could also be used for things like sports scores, weather forecasts, and entertainment listings.
Teletext works by transmitting the text and graphics data as part of the vertical blanking interval (VBI) of the television signal. The VBI is a period of time during which the television display is blank, and is used to transmit various types of data that are not part of the actual video signal. The teletext data is encoded in a special format called “teletext packets,” which can be decoded by a teletext decoder built into the television or other device.
To access the teletext information, the viewer would use a special button on the television remote control or set-top box to bring up the teletext menu. From there, they could navigate through the different pages of text and graphics using the remote control. Teletext was popular in many countries, particularly in Europe, and was a common feature of television sets until the widespread adoption of the internet made it largely obsolete.
Read more in Flussonic documentation: Teletext and Closed Captions