Castanets have existed for at least 2000 years. Described as clappers or finger cymbals, they were used extensively in ancient Greek and Egyptian cultures. Their contemporary name comes from the Spanish word castana, or 'chestnut'.

Ranging in size from around two to seven inches, these handheld percussive instruments are made from small disks of metal, hardwood or nutshells which have been slightly hollowed along one side to increase their resonance.

Castanets are often played by dancers, one pair held in each hand; their intricate rhythms match and articulate the steps of the performer. It is said that the 'macho' (or male) pair in one's left hand plays a basic rhythm, while the 'hembra' (or female) pair in the right hand articulates a full dance rhythm.

Although the specific origin of castanets is not known, their current history is clear: anywhere Spanish (and prior to that, Moorish) communities have travelled, these enduring instruments are usually found as, for example, in much of South and Central America. They are commonly used by Spanish dancers to accompany dances such as the bolero, cachucha, etc. with a sharp clapping sound.

Castanets also feature in some contemporary Western orchestral repertoire, where they are usually attached to handles so that they can be played more easily.