They debuted in 1994 as "The Reason I Wanted You". In the 1st album, Kim Sung-soo, Lee Jae-hoon, Yoo Chae-young and Choi Jun-myung were four, but from the second album, Yoo Chae-young and Choi Jun-myeong withdrew and while female member Yuri joined them, Kim Sung-soo and Lee Jae-hoon together acted as a three-member group.
Vocal Lee Jae-hoon's steady singing skills, fun songs and images continued to be popular. Cool's songs were simple and easy to sing, so it was easy for the general public to love it. Their songs were often in the top sung songs in Korean karaoke. They mainly performed in dance and ballad music. In 2002, they received the Golden Disk Award, recording their seventh album as the year's best-selling album.
On August 2, 2005, they announced their disbandment, but on July 25, 2008, they started activities again after releasing the 10.5 "I Want to Love" album. In summer 2009, they released the 11th regular album. In 2014, they celebrated 20th anniversary with the release of "Goodbye" and began touring with broadcasting activities such as "Hidden Singer" and "Infinite Challenge."
^Hong, Je-seong (December 14, 2002). "제17회 골든디스크상 대상에 그룹 쿨" [Group Cool wins at the 17th Golden Disk Awards]. SBS News (in Korean). Retrieved August 24, 2018.
^"조성모 골든디스크 대상" [Jo Sung-mo wins at Golden Disc Awards]. Segye Ilbo (in Korean). Naver. December 5, 2003. Retrieved December 11, 2022.