The Apology of Socrates is Plato's version of the speech given by Socrates as he unsuccessfully defended himself in 399 BC against the charges of "corrupting the young, and by not believing in the gods in whom the city believes, but in other daimonia that are novel" (24b). "Apology" here has its earlier meaning (now usually expressed by the word "apologia") of speaking in defense of a cause or of one's beliefs or actions (from the Ancient Greek ἀπολογία). (Summary by Wikipedia)