In his first competition, Sophocles took first prize--defeating none other than Aeschylus himself. More than 120 plays were to follow. He would go on to win eighteen first prizes, and he would never fail to take at least second......Of Sophocles' more than 120 plays, only seven have survived in their entirety. Of these, Oedipus the King is generally considered his greatest work. This tragedy of fate explores the depths of modern psycho-analysis as Oedipus unwittingly kills his father and marries his mother in an attempt to avoid the very prophecy he ultimately fulfills." (Sophocles)
For more information on Sophocles life - http://www.imagi-nation.com/moonstruck/clsc1.htm was a great source of information.