[Excerpted from http://faculty.gvsu.edu/websterm/Tragedy.htm]
Origins:
Tragedy's origins are obscure, but it apparently started with the singing of a choral lyric (called the dithyramb) in honor of Dionysus. It was performed in a circular dancing-place (orchestra) by a group of men who may have impersonated satyrs by wearing masks and dressing in goat-skins. (The Greek word tragoedia means "goat-song.") Eventually, the content of the dithyramb was widened to any mythological or heroic story, and an actor was introduced to answer questions posed by the choral group. (The Greek word for actor is hypokrites, which literally means "answerer." It is the source for our English word "hypocrite.") Tragedy was recognized as an official state cult in Athens in 534 BC. According to tradition, the playwright Aeschylus added a second actor and Sophocles added a third.
Performance:
Greek tragedies were performed in late March/early April at an annual state religious festival in honor of Dionysus. The presentation took the form of a contest between three playwrights, who presented their works on three successive days. Each playwright would prepare a trilogy of three tragedies, plus an unrelated concluding comic piece called a satyr play. Often, the three plays featured linked stories, but later writers like Euripides may have presented three unrelated plays. [. . .] The Greek theatre was in the open air, on the side of a hill, and performances of a trilogy and satyr play probably lasted most of the day. Performances were apparently open to all citizens, including women, but evidence is scanty. The theatre of Dionysus at Athens probably held around 12,000 people (Ley 33-34).
The presentation
of the plays probably resembled modern opera more than what we think of as a
"play." All of the choral parts were sung (to flute accompaniment)
and some of the actors' answers to the chorus were sung as well. The play as
a whole was composed in various verse meters. All actors were male and wore
masks, which may have had some amplifying capabilities. A Greek chorus danced
as well as sang. (The Greek word choros means "a dance in a ring.")
No one knows exactly what sorts of steps the chorus performed as it sang. But
choral songs in tragedy are often divided into three sections: strophe ("turning,
circling"), antistrophe ("counter-turning, countercircling")
and epode ("after-song"). So perhaps the chorus would dance one way
around the orchestra ("dancing-floor") while singing the strophe,
turn another way during the antistrophe, and
then stand still during the epode.