The Glee cast has released sixteen soundtrack albums, six compilation albums, eleven extended plays (EPs), and 460 singles. Glee features on-screen performance-based musical numbers, most of which are cover versions of popular songs, with genres ranging from R&B and pop to country and show tunes. The cast consists of fifteen main characters; some actors were cast following Broadway theatre experience while others were required to audition to prove singing and dancing capabilities. Recordings of performances on the show are sold as singles the week of broadcast, available for digital download.