E4 is a British digital television channel launched as a companion to Channel 4 on 18 January 2001. The "E" officially stands for entertainment (although it can also be seen as a sly reference to the drug Ecstasy), and the channel is mainly aimed at the lucrative 18 - 35 age group. Programming includes US imports such as Friends, ER, The Sopranos, Six Feet Under, The West Wing and Desperate Housewives, sometimes premiering on E4 before being broadcast on Channel 4, plus lots of home-grown chat and reality shows.

Every year, whilst the Big Brother game show airs, E4 devotes much of its schedule to Big Brother programming such as live coverage from inside the house, interactive features that give access to additional camera angles within the house, Big Brother voting options and Big Brother "catch up" shows (i.e., repeats). Big Brother coverage is among the highest rating programming on the channel, and comes at a time when most of the years American imports have ended.

On 16 December 2004, Channel 4 was reported as considering moving the subscription channel to Freeview, effectively allowing the channel to become free to air [2]. A Channel 4 executive was later quoted as saying it was "not if, but when" E4 would be going free-to-air [3]. The channel is believed to have earmarked the end of 2005 for E4 to go free-to-air.