It's very hard to know. Since Socrates didn't write any treatises of his own, we only know him through the people who wrote about him. Our sources are primarily his contemporary Aristophanes (who mocked his philosophies in the comedy Clouds) and his students Xenophon and Plato.

The trouble is that each of these authors paint a very different picture of Socrates, and there is no independent source that would allow us to establish which of the three is closest to the truth. The character of the "real" Socrates is therefore an age-old controversy, known as the Socratic Problem. Scholars are particularly torn over whether Socrates was a pragmatist and moralist, as he is in Xenophon's work, or a more abstract thinker, as he is in Plato's. Both these images ultimately suited the authors who created them, and Socrates may have been like one or the other, or both, or neither.

Still, there are a couple of things on which our sources are in agreement. Socrates disdained the sophists of his day, who taught what they had learned for a fee; instead, he instructed all who would hear for free, and bothered people on his own initiative whether they were interested or not. He made a great display of his poverty to underline that he was not trying to get rich off of his cleverness. In fact, he understated his own wealth; he went about looking like a beggar, but his military service as a hoplite on several campaigns suggests that he must have been of more than moderate means. Finally, he had a famous way of teaching, still known as the Socratic method: by continually questioning the underlying assumptions on which people based their beliefs about the world, he revealed to them that they knew and understood much less than they thought they did. This did not mean that he believed he himself knew better; his concept of wisdom was a thorough awareness of the limitations of our own knowledge.