Sophocles wrote 120 or more plays during his life, but only seven have survived in a complete form, namely Ajax, Antigone, Maidens of Trachis, Oedipus the King, Electra, Philoctetes and Oedipus at Colonus.
In addition his plays are outstanding for their straightness of plot, the nobility of the characters.
Among Sophocles’ earliest innovations was the addition of a third actor, further reducing the role of the chorus and creating greater opportunity for character development and conflict between characters.
Early tradition holds that formal theatre in Athens evolved from festivals related to the cult of Dionysus, the Greek god of fertility and wine.
Furthermore the theaters were large, open–air structures constructed on the slopes of hills. They consisted of three principal elements: the orchestra, the skene and the audience. The centerpiece of the theatre was the orchestra or "dancing place", a large circular or rectangular area. The orchestra was the site the choral performances, the religious rites, and, possibly, the acting. …
