The Greek art of the drama had its roots in religious festivals for the gods, chiefly Dionysus, the god of wine.
During Aeschylus' lifetime, dramatic competitions became part of the City Dionysia in the spring. The festival began with an opening procession, continued with a competition of boys singing dithyrambs, and culminated in a pair of dramatic competitions. The first competition, which Aeschylus would have participated in, was for the tragedians, and consisted of three playwrights each presenting three tragic plays followed by a shorter comedic satyr play. A second competition of five comedic playwrights followed, and the winners of both competitions were chosen by a panel of judges.
Aeschylus entered many of these competitions in his lifetime, and various ancient sources attribute between seventy and ninety plays to him. Only seven tragedies have survived intact: The Persians, Seven against Thebes, The Suppliants, the trilogy known as The Oresteia, consisting of the three tragedies Agamemnon, The Libation Bearers and The Eumenides, and Prometheus Bound (whose authorship is disputed). With the exception of this last play—the success of which is uncertain—all of Aeschylus' extant tragedies are known to have won first prize at the City Dionysia. The Alexandrian Life of Aeschylus indicates that the playwright took the first prize at the City Dionysia thirteen times. This compares favorably with Sophocles' reported eighteen victories (with a substantially larger catalogue, at an estimated 120 plays), and dwarfs the five victories of Euripides (who featured a catalogue of roughly 90 plays).
When Aeschylus first began writing, the theatre had only just begun to evolve, although earlier playwrights like Thespis had expanded the cast to include an actor who was able to interact with the chorus. Aeschylus added a second actor, allowing for greater dramatic variety, while the chorus played a less important role. He is sometimes credited with introducing skenographia, or scene-decoration, though Aristotle gives this distinction to Sophocles. Aeschylus is moreover said to have made innovations in costuming—making the costumes more elaborate and dramatic, and having his actors wear platform boots (cothurni) to make them more visible to the audience. According to a later account of Aeschylus' life, as they walked on stage in the first performance of the Eumenides, the chorus of Furies were so frightening in appearance that they caused young children to faint, patriarchs to urinate, and pregnant women to go into labor.