Socrates was Plato's teacher and became the central philosophical figure in many of Plato's writings. Socrates wrote nothing himself, so most of what we know of him comes from Plato's writing.
Socrates is famous for statements such as "know thyself" and he never claimed to know more than he actually did. In Plato's dialogues, Socrates uses what we call the Socratic method. Socrates would listen to another's argument and then he would ask questions that revealed the inconsistencies of his opponent's argument. Using this method, Socrates would guide his opponent to a new understanding by questioning in this way.
Socrates devoted his time to seeking wisdom, usually by asking questions, particularly in conversations with others. He sought the improvement of the soul (mind/spirit) above any other materialistic needs and desires.
In The Apology, Socrates defends himself against his accusers. In typical Socrates fashion, Socrates questions his accusers thereby revealing the lack of logic, justice, and consistency of their arguments. In one section, Socrates points out how Meletus charges him with being an atheist while also believing in other gods:
But still I should like to know, Meletus, in what I am affirmed to corrupt the young. I suppose you mean, as I infer from your indictment, that I teach them not to acknowledge the gods which the state acknowledges, but some other new divinities or spiritual agencies in their stead.
Socrates continues questioning Meletus, prompting him to say that he believes Socrates to be a complete atheist. It is easy to see how Socrates reveals the inconsistency of Meletus' arguments with this example. Socrates then says, "For he (Meletus) certainly does appear to me to contradict himself in the indictment as much as if he said that Socrates is guilty of not believing in gods, and yet of believing in them--but this is not a person who is in earnest."
Socrates was accused of corrupting the youth of Athens. However, he never indoctrinated others in the way the state, government, or religious doctrine does. Socrates didn't provide a doctrine or a fixed set of beliefs; rather, he raised thought-provoking questions.