What is Street Photography?

So in Specialization class, I have decided to focus on Street Photography.  So many times the question has come up to me of what is Street photography?  Who says what is appropriate for Street photography? Do portraits in a Street environment constitute as Street?  I have always been fond of Landscapes.  Based on that and the recent curiosity of what goes on in Chicago, I concluded to focus on Street photography.  Does anyone have any ideas on what I could focus on while shooting?  I have been told to stay away from the poverty side of things because it is over done and focus on reality.  Though I have always thought that reality is poverty in its prime? I suppose there are many takes on this question.  Please share your thoughts.