Welcome to the jazz theory section of JazzGuitarLessons.net ... here you'll be able to satisfy your intellectual cravings for understanding how music works theoretically.
You'll find out about how scales and chords are constructed (and why!) plus many articles addressing a wide range of theory topics such as progressions, modes, chords with alterations, key signatures, cadences, etc.
So, what IS jazz theory? The way it's going to be presented on this website, jazz theory is like popping up the hood and looking at a car's engine! You'll understand why you're allowed to speed up, slow down, make wide or sudden turns, and so on. In brief, music theory is how we organize the sounds we have on our instruments into a logical system (that's the "engine")...
Before you start reading the pages and articles above, I believe it's important for you to understand this: jazz theory, as much as you can learn from it on a written page, really lies in YOUR EARS. The systems we use to explain what we're doing have to be identifiable *by sound*. That being said, always make sure that what you're studying in theory is understood well and that you can HEAR IT (and I mean away from your instrument).
Be wary of websites where all the "jazz instruction" they present is always jazz theory...
For instance, you find an article titled "15 Things Every Jazz Improviser Should Know" and it only discusses scales, arpeggios, chords, etc. (jazz theory stuf). Those websites are dime a dozen: lots of emphasis on the theory and technicalities, not much music played in the end. If you don't learn about actual improvisation in the articles, then it's not about improv, is it? I mean, sure... you have to know your scales in the end, but scales is not "what every improviser should know"!!!
Music is about expression, feelings, groove, perception, etc. So, it doesn't matter if you know all the modes to "harmonic major with a bad tempered fifth" and that you can play them in 17 positions on the guitar... the bottom line is how you sound when you play! Zat sit! (However little or big you know about jazz theory.)
To summarize my point: learning all the jazz theory won't necessarily make you into a great player. Furthermore, if you DO become a great player, then I'm sure along the way you'll pickup all the theory "you need" in order to execute your musical ideas brilliantly. (-:
The No Nonsense Series: If you already know some stuff about chords, then the "No Nonsense Guides" are a great way to get into jazz theory without being overwhelmed with too many notes, scales, modes, etc. In fact it's some sort of simplification of some of theory's intermediate concepts. (Not completely for beginners, yet not too advanced).