Music that is performed by an ensemble of singers, whether a choir, chorale, or chorus.

A vocal ensemble which sings in a church, or sings exclusively sacred music, is generally called a choir, whereas an ensemble which performs the non-soloist parts of an opera or musical theatre production (or sometimes an oratorio) is called a chorus. For most other ensembles, those two words may be used interchangeably.

Other equivalent terms, often used in the names of choirs to provide variety, include chorale. There are also terms for more specific types of choir, such as glee club, show choir, barbershop quartet and madrigal group. A choir usually has 8 or more singers, typically with 2 or more singers on each part. A chorus is typically larger still, with many singers on each part.

The earliest form of notated choral music in western Europe is Gregorian chant, an a cappella tradition which maintains to the present day.