Exo ( /ˌɛks ˈəʊ/ eks-oh; Korean: 엑소; stylized as EXO) is a Chinese–South Korean boy band produced by S.M. Entertainment. Formed in 2011 inSeoul, South Korea, Exo comprises twelve members separated into two subgroups, Exo-K and Exo-M, promoting their music simultaneously in bothSouth Korea and China respectively. Their name was taken from exoplanet, a term referring to planets outside of the Solar System. Their debut single “Mama” was released on April 8, 2012, followed by the release of their debut EP Mama on April 9, 2012.