Homophony means music in which the voices or instruments sing or play chords (chords are when two or more notes are played together.) In homophonic music all the choir (sopranos, altos, tenors and basses) are singing the same words at the same time. There is a tune on top and the lower parts are the accompaniment. This is what happens in hymn singing. The opposite is polyphony. Polyphonic writing is more complicated: the choir sing different melodic lines at the same time (see counterpoint). The terms "homophony" (literally: "one sound") and "polyphony" (literally: "many sounds") are mostly used for choir music.