BBC Two is celebrating 40 years of broadcasting to the nation on Tuesday.
Some of the UK's favourite comedies started on BBC Two
The channel launched on 20 April 1964 with children's show Playschool, and transmitted the country's first colour broadcast on 1 July 1967.
Over the years it has developed a reputation for screening cutting edge drama, documentaries and comedy series.
Programmes that started on BBC Two include Match of the Day, Life On Earth, drama Boys From The Blackstuff and Bafta-winning comedy The Office.
BBC Two controller Jane Root said it had been a success because it had kept to a similar formula throughout the years.
"When BBC Two was started the idea was to have comedy, and drama, and news, and sports, and to try and innovate in all of them, to do different things," she told BBC One's Breakfast.
"The programmes have changed but that central mission has stayed the same all the way through."
Comic actor Reece Shearsmith, from The League of Gentlemen, praised the channel for taking a risk with "daring" comedy.
"Our thing, its natural home was always (BBC) Two," he told Breakfast.
"For what we wanted to do...Two was exactly the right place to do it and experiment with how far you dare do it."
Many shows began life on BBC Two before being transferred to BBC One in order to attract a bigger mainstream audience.
These include the satirical news panel game Have I Got News For You, sitcom Fawlty Towers and quiz show The Weakest Link.
BBC Two was home to some of the UK's most celebrated factual programmes, such as Civilisation, The Great War and a History of Britain.
Dramas that started out on the channel included I, Claudius, This Life, Edge of Darkness and Our Friends in the North.
And it first aired household-name comedies such as Yes, Minister, The League of Gentlemen, Red Dwarf and The Young Ones.
The channel is also renowned for its arts coverage, with pioneering shows such as Arena, The Late Show and The Old Grey Whistle Test.
But it has attracted criticism in the past few years for a perceived switch to more lifestyle and makeover shows such as Ground Force and Changing Rooms.
Despite the increased take-up of multi-channel TV, however, it has managed to maintain its audience share of about 10%.
BBC Two is known for its innovative programming
It recently embraced the idea of interactive TV with programmes such as the history series Great Britons, and Restoration, which followed the fate of British heritage sites.
Happy Birthday BBC Two is being screened on the channel on Tuesday evening at 2000 BST, featuring people who have worked both behind and in front of its cameras over the years.