A choir is a group of singers that perform various songs, either in unison or in harmony. The music they sing is often called a chorale. If a chorale is sung in unison, it means that everyone in the choir sings at the same pitch, while a harmony consists of many voices singing at different pitches at the same time.

A choir normally consists of at least eight members. Smaller groups are often called vocal groups or ensembles. A choir can sing with or without the accompaniment of music instruments, depending on the type of music. Most choirs have a conductor that directs the choir, so that they know when to begin or end their songs, when to increase or lower their volume. The conductor also signals transitions between the different voices. There are many types of choirs for both children and adults of all ages, and in all genres. Singing in a choir is a social activity, and many choirs go on trips, participate in festival and perform concerts for audiences.