A style found in almost all types of music, from tribal to classical to folk to jazz to rock to rap. The melody is split between two different instruments or sections, each playing a brief snippet, so that it seems like one instrument is echoing or responding to the other.

A good example is found in the chorus of the Rap song O.P.P.:

Lead Singer:You down with O.P.P?
Backup singersYeah, you know me!!