Socrates, the "gadfly of Athens," was an ancient Greek philosopher, who lived between approximately 470 and 399 BC. He is best known for his method of argument (elenchus, or the Socratic Method), which poses questions that may expose logical errors underlying an opponent's argument, though he usually stated that his purpose was not to argue but to pursue the truth in alliance with his opponent. Socrates had served in the army in his youth, like all Greek men of his time. To modern readers he is most familiar as a character in many books by his disciple Plato or his contemporary Xenophon. If Socrates wrote any books himself they are lost. Eventually the courts of Athens found him guilty on charges of impiety and corrupting the youth, and sentenced him to drink hemlock, a poison that took his life. Socrates had an opportunity to escape from prison, but declined to do so. 
Socrates was what we call a "gadfly" today, persistently questioning and criticizing others in authority. Plato portrayed Socrates as a fly that would awaken the sleeping horse of Athens by repeatedly biting it, and several modern translations of Plato's Apology even use the term "gadfly".
His elementary school education included literature, music and gymnastics. He then studied Philosophy and Public Speaking. He was a sculptor like his father. His statue, The Three Graces, was at the entrance to the Acropolis for over six hundred years. He had no formal students. A veteran of the Peloponnesian war, he began philosophical conversations and debates with people in restaurants and stores. His teachings included that ignorance is the cause of all vice, and he emphasized being rational and questioning one’s own thoughts and inner voice. He was condemned by a small majority rather than unanimously. His defense was that what he did wasn’t bad enough to receive death, but might be worth a small fine.
The question of the historical Socrates
The major problem in studying the thought of Socrates is that we have to rely on the writings and reports of others since Socrates himself wrote nothing. There is also no historical record of anybody named Socrates ever existing; a vast majority of what we know of the man comes from his pupils, especially Plato, who wrote more about Socrates than anybody else.
Aristotle examines Socrates in his Metaphysics, and Xenophon provides some additional information. But Plato, who was Socrates' pupil, is our principal source of information. He (Plato) wrote numerous dialogues in which Socrates figures either as the main speaker or as a secondary character. The problem is separating out from these dialogues what is Socrates and what is Plato. And the chief question is the origin of Plato's "Forms Theory".
Coopleston, in his History of Philosophy, takes the traditional view, largely accepting Aristotle who stated that Socrates did not "separate" the Forms. On this view, although the historical Socrates is presented, especially in the early dialogues, the fully developed theory of Plato's is an elaboration or development of Socrates' views and, especially in his later writings, Plato has used the character of Socrates to expound these views.
There are two aspects of the historic Socrates' life that can be reasonably assumed to be true because they appear to be consistent among most accounts: that he was a critic of Athenian democracy and that he was executed by the state because of it.
Some famous Socrates quotes
- The unexamined life is not worth living.
- Death may be the greatest of all human blessings.
- Do not do to others what angers you if done to you by others.
- Having the fewest wants, I am nearest to the gods.
- I know nothing except the fact of my ignorance.
- based on Funk & Wagnals New Encyclopedia. Socrates. F & W’s bibliography for their article on Socrates includes: Guthrie, W.K.C. A History of Greek Philosophy. 1981. Cambridge. (about the course of Greek philosophy), and Montuori, Maria. Socrates: Philosophy of a Myth. Humanities. 1981. (about Socratic mythology.) and other books.
Plato, Christopher Gill, The Symposium. London: Penguin Books, 1999