A chorus (also called a choir) is a group of singers.  Unlike any other type of musical ensemble, the age and gender of the singers has a significant impact on the sound that is produced. Therefore, there are many types of choirs: choirs for adults and children, women and men, and school and community choirs where the singers are grouped by age. However, it is not absolutely necessary to place restrictions on the makeup of a chorus.

Choral music dates back at least as far as ancient Greece. Archaeologists have unearthed stone carvings of written music from the 2^nd century BC. The Greeks used choral music as part of their theatrical productions and religious rituals. Since then, choirs have sung in churches, schools, and concert halls. There are choirs that sing classical music, jazz, pop and show tunes, and folk music (or a mixed repertoire of all those styles.)
 

A chorus is typically led by a conductor. It is the job of the conductor to interpret the composer’s intent for the music. (S)he achieves this by reading the printed music (called the score), and by researching the song’s history. The conductor guides the chorus in their preparation of the music so that they can deliver the best possible performance.

Choirs frequently sing with piano accompaniment, but some music calls for other instruments. There are even some songs written for combined choir and orchestra.
 

Some choral music has no instruments at all. The term for unaccompanied singing is a cappella. “A cappella” literally means “of the chapel,” because this style of singing was used in medieval Christian churches where instruments were not allowed.

The prevailing belief back then was that voices were a gift from God, and therefore they were more sacred than instruments. This attitude persisted until the Baroque period. Although instruments are now permitted in nearly all churches, the use of group singing in worship is almost universal.
 

Today the term “a cappella” is most frequently used in reference to small groups of singers who perform arrangements of contemporary music. These a cappella groups, which can be male, female, or coed, use their voices to imitate the sounds of instruments – even drums!