Texting celebrates its twentieth anniversary
3 December 2012 Last updated at 00:46 GMT
In a world first, on December 3 1992, an engineer sent the message "Merry Christmas" from a PC to a mobile device using Vodafone's UK network.
This is regarded as the first text message. It has now become one of the most popular forms of communication, with hundreds of thousands being sent every day over both traditional mobiles, and smartphones.
BBC News asked a random selection of Londoners to explain when it was appropriate to text, and what life was like before the invention.
Despite the prevalence of texting, people were surprisingly critical about it.
Video Journalist: Dougal Shaw