All classical Greek tragedies make use of a chorus.
In classical Greek theater, there were three elements to any theatrical production: actors, spectators and the chorus. The chorus is the oldest element of any Greek performance, and comes from the Greek word meaning "dance." A Greek chorus would often dance and sing during a performance, and ranged in number from 15 to 50 men. It served a number of functions for audiences when used in tragedies.
Song and Dance
Greek drama was a form that evolved out of song and dance; as such, a chorus would often incorporate song and dance into the events of the play. The chorus would have two important songs in a tragedy: a "parados," or entrance song, and the "stasima," or choral song used to propel the narrative.
Provide Background Information
A chorus would often provide audience members with background information that applied to the events on stage. Such information would help audience members understand the performance. The chorus would do this through song and dance or by speaking their lines in unison.
Act as a Character
Often, the chorus represented an anonymous crowd that symbolized the people who lived within the play's settings, such as the Theban citizens in "Oedipus Rex."
Act as the Audience
One of the most important functions of a Greek chorus was to act as the ideal spectator; that is, to act how the playwright had hoped the audience would respond. It was to act as an emotional bridge, connecting the actors to the spectators, and functioned on stage as if the audience was actually a part of the action, questioning the characters' motives and otherwise commenting about the events on stage.
