A duet is a musical composition for two performers in which the performers have equal importance to the piece, often a composition involving two singers or two pianists. It differs from a harmony, as the performers take turns performing a solo section rather than performing simultaneously. A piece performed by two pianists performing together on the same piano is a "piano duet" or "piano four hands".[1] A piece for two pianists performing together on separate pianos is a "piano duo".
"Duet" is also used as a verb for the act of performing a musical duet, or colloquially as a noun to refer to the performers of a duet.
A musical ensemble with more than two solo instruments or voices is called a trio, quartet, quintet, sextet, septet, octet, etc.