The term Gospel quartet refers to several different traditions of harmony singing. Its origins are varied, including 4-part hymn singing, shapenote singing, barbershop quartets, jubilee songs, spirituals, and other Gospel songs. Gospel quartets sing in four-part harmony, with parts given to a tenor, or highest part; lead, which usually takes the melody; baritone, which blends the sounds and adds richness; and the bass, or lowest part. It is not uncommon for some quartets to switch parts between members for given songs.