We don't really know much about Socrates. Or at least most of what we know is from the writings of his students.
Plato is frequently viewed as the most informative source about Socrates'
life and philosophy.[5] At the same
time, however, many scholars believe that in some works Plato, being a literary
artist, pushed his avowedly brightened-up version of "Socrates" far beyond
anything the historical Socrates was likely to have done or said; and that
Xenophon, being an historian, is a more reliable witness to the historical
Socrates. It is a matter of much debate which Socrates Plato is describing at
any given point—the historical figure, or Plato's fictionalization
He was a teacher, that we know. And from him we get the teaching method of asking questions so as to engage the subject more fully. He is widely viewed as a critic of the leaders of Athens and from him we get the concept of the 'gadfly'.
Socrates, through his students, laid the groundwork for much of Western Philosophy and in that sense is an excellent place to start.