A clap is the sound made by striking together two flat surfaces, as in the body parts of humans or animals. Humans clap with the palms of their hands, often in a constant drone to express approval (see applause), but also in rhythm to match sounds in music and dance. Seals are among the animals that clap.

There is a well-known koan that involves, superficially, consideration of the act of clapping: "What is the sound of one hand clapping?"

Clapping is occasionally used as a percussion element in music, particularly in Gospel music. One composition by Steve Reich, Clapping music, is entirely performed by clapping.

Pedagogical applications

Music students often clap the rhythm of written music to help learn the value of different notes and to get accustomed to the rhythm of new pieces.

See also

• Acoustics

Clapping can be used in acoustics to check the reverberation time of a room. The clap's decay time determines this. Pretty much any sound can be used to do this but a sound of a hand clap delivers a clear frequency and is readily available.