Socrates left no writings, but we know of his teachings through the writings of his pupil Plato (c.428-c.348), who presented many of his works in the form of Dialogues in which Socrates was the main speaker, though it is probable that many of the ideas that are put into his mouth are those of Plato. Information on his life is mainly in the Apology, Crito and Phaedo.
More details of the life of Socrates are given in several works of his follower, the military historian Xenophon (c.435-c.354), including Memorabilia Socratis, and Apologia (Socrates' Defence before the Jury). Socrates was also satirised as a sophist in the play The Clouds by the comic dramatist Aristophanes (c.448-c.385).
The 'Socratic Method' was to get people to say what they thought and then to question them to reveal inconsistencies. Earlier philosophy is termed 'Pre-Socratic'. He increased the emphasis on ethics and the 'considered life'.
He proved to be too successful in getting young men to think for themselves, so that they started to dispute with their elders. He was charged by the elders with leading youth astray, and sentenced to die, by drinking hemlock. He is often thought of as a martyr of rationalism.
He was born in Athens, the son of a stonemason. His relationship with his wife Xanthippe was stormy, and he is represented as snub-nosed and with a paunch. He fought as a hoplite in the Peloponnesian war. There is a bust of Socrates on the frontage of Leicester's Secular Hall.
Chambers Biographical Dictionary 2007, entry for Socrates, which cites W. K. C. Guthrie Socrates (1971), and entries for Aristophanes, Plato and Xenophon.