It premiered at 20:00 BST on 28 June 2008 and was hosted by Ben Shephard and Denise Van Outen.
The studio audience of 100 people all attempt to sing to win a potential jackpot of £50,000.
In the first round, all 100 people sing along to a song, but five performances of the song are selected at random and judged by a super computer called SAM (short for Sound Analysis Machine).
The two that score the highest go through to a "pitch battle", for a place in the semi-final round.
The main idea of the game it to hit and hold the "hot notes", as close to the original song as possible.