19 tracks
CD1: Over the Rainbow "A" "Mach" "Gonna Gonna Go!" "Kiss! Kiss! Disco!" "Touch Me, Feel Me, Love Me" "Alright" "Not Your Girl" "Energy" "Hello" "Gossip Girl" CD2: Korean songs "Not Your Girl" "Gossip Girl" "I Believe" "Kiss" "A" "Mach" "To Me" "Sweet Dream" "Candy Girls!" * * Bonus track

19 tracks
CD1: Over the Rainbow "A" "Mach" "Gonna Gonna Go!" "Kiss! Kiss! Disco!" "Touch Me, Feel Me, Love Me" "Alright" "Not Your Girl" "Energy" "Hello" "Gossip Girl" CD2: Korean songs "Not Your Girl" "Gossip Girl" "I Believe" "Kiss" "A" "Mach" "To Me" "Sweet Dream" "Candy Girls!" * * Bonus track

"A" is a song by South Korean girl group Rainbow. The song was released on August 12, 2010, and was later included on their second mini album So Girls.

A teaser photo with the concept of the song was released in August 4. A teaser of the music video was released in August 10 and the full music video in August 12, along with the release of the single.

The song was produced by Han Jae Ho and Kim Seung Soo (also known as Sweetune), who also produced the songs "Rock U", "Pretty Girl", "Honey", "Wanna", "Mister" and "Lupin" for their label-mate KARA.

The promotions of the song started on August 13, in the KBS's Music Bank and also promoted on MBC's Music Core, SBS's Inkigayo and Mnet's M! Countdown.

In the debut week, the song debuted at number 50 and climbed to the position 11 on the following week. The highest peak of the song is number 9, ranked in the week of September 4. The song ranked number 80 in Gaon's Yearly chart with 337,665,388 points and with 1,617,074 digital copies sold.

CD1: Over the Rainbow

CD2: Korean songs

The song was re-record in Japanese as the group's debut single in Japan. It was released digitally on September 7, 2011 and physically on September 14 in 4 different versions: 3 limited editions (CD+DVD, CD + 32-pages photobook and CD Only + Bonus track) and a regular edition.

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Wikipedia