From Valerie Dawning
Ceefax was the world’s first teletext information service launched by the BBC in 1974. So-called because it enabled viewers to ‘see the facts’ at their fingertips; it provided quick updates on news headlines, sports scores, weather forecasts and TV listings in the pre-internet era. It was developed by BBC engineers who, while exploring ways to provide subtitles on TV programmes, discovered that they could transmit full pages of text information in the spare lines at the top of pictures transmitted on the analogue TV signal. However, after 38 years on the air, it was turned off when the digital switchover was completed in 2012.
Answered by Joanna Stass for Brain Dump in How It Works issue 107