B1A4 is a South Korean boy band formed by WM Entertainment. The group debuted on April 23, 2011 with the single “O.K” from the EP Let’s Fly, after being introduced to the public through a webtoon. They have released nine studio albums (four Korean and five Japanese) and seven EPs, as well as four compilation albums. The group had considerable commercial and critical success in both the Korean and Japanese markets. They have also toured in the United States.