Twitter

Twitter was a social network in the 21st century.

History
In 2009, after the Torchwood Three team accidentally drove off the Severn Bridge, they heard a mysterious voice under the water. Back at the Hub, Ianto Jones stated that it was a hit on Twitter. (BBCR: Submission)

In 2011, a news reporter stated that "Miracle Day" had been "trending", terminology often associated with Twitter. (TW: The New World)

In the same year, Patricia Menzies said that her phone could not access Twitter. (BFA: The Crimes of Thomas Brewster)

When the Doctor's TARDIS arrived on Apalapucia, Amy Pond asked for her mobile phone, as she wanted to update Twitter. (DW: The Girl Who Waited)