Anagnorisis (/ˌænəɡˈnɒrᵻsᵻs/; Ancient Greek: ἀναγνώρισις) is a moment in a play or other work when a character makes a critical discovery. Anagnorisis originally meant recognition in its Greek context, not only of a person but also of what that person stood for. Anagnorisis was the hero's sudden awareness of a real situation, the realisation of things as they stood, and finally, the hero's insight into a relationship with an often antagonistic character in Aristotelian tragedy.
In his Poetics, as part of his discussion of peripeteia, Aristotle defined anagnorisis as "a change from ignorance to knowledge, producing love or hate between the persons destined by the poet for good or bad fortune" (1452a). It is often discussed along with Aristotle's concept of catharsis.
In the Aristotelian definition of tragedy, it was the discovery of one's own identity or true character (e.g. Cordelia, Edgar, Edmund, etc. in Shakespeare's King Lear) or of someone else's identity or true nature (e.g. Lear's children, Gloucester's children) by the tragic hero.
Aristotle was the first writer to discuss the uses of anagnorisis, with peripeteia caused by it. He considered it the mark of a superior tragedy, as when Oedipus killed his father and married his mother in ignorance, and later learned the truth, or when Iphigeneia in Tauris realizes in time that the strangers she is to sacrifice are her brother and his friend, and refrains from sacrificing them. Aristotle considered these complex plots superior to simple plots without anagnorisis or peripeteia, such as when Medea resolves to kill her children, knowing they are her children, and does so.