ABBA was a Swedish pop music group, the most successful to date from that country. The group was formed around 1970 by Björn Ulvaeus, Benny Andersson, Agnetha Fältskog, and Anni-Frid Lyngstad, and the name ABBA comprises their first initials. They became widely known when they won the 1974 Eurovision Song Contest with "Waterloo". Abba split up in 1982
Abba were well known for their colourful costumes (the epitome of 1970s fashion), and also for the videos which accompanied some of their biggest hits -- these being among the earliest examples of the genre. All of Abba's videos were directed by Lasse Hallström, who also directed a feature-length film about the group, Abba - The Movie. Abba chose to make them because they preferred perfecting the songs rather than making personal appearances in all the countries where the song was likely to be a hit. Some of these videos became classics. For example, the video of "Knowing Me, Knowing You" was satirised on the BBC comedy show, Not the Nine O'Clock News, as "Super Dooper". The title Knowing Me, Knowing You was also borrowed for a spoof chat show on BBC radio and television, starring Steve Coogan as Alan Partridge, who always entered the studio shouting "Aha!", this being the next word in the lyrics of the original song.
Source - http://www.abba-story.com