Unaccompanied part songs, also known as 'glees' (5 letters), are a type of choral music that is sung without any instrumental accompaniment. They are typically composed for three or more voices and often feature a soloist. Glee clubs, which are groups of singers who specialize in performing glee music, have been popular since the 18th century. Glee music has been used in many different genres, from classical to folk to pop.