Now that you know everything about harmony...oh, wait. Because regular old harmonies have nothing on jazz. So for today's Blogging A-to-Z challenge entry I'm going to lift up the curtain on some pretty wild stuff.
I'm actually not going to have a lot of musical examples today. I'm merely going to point you toward other places that do it better.
I will, however, draw your attention to the greatest jazz musician in history: Bach. He improvised the way that other people breathe. And he influenced modern jazz artists hundreds of years later. Just one example, Nina Simone. Listen to the fugue she injects about a minute in:
Or more recently, here's Donal Fox doing improvising on a Bach prelude:
The problem with this format is that jazz is a topic just as large as music theory. So if this post has done nothing more than gotten you to listen to a couple of jazz pieces, that's a success.