Originally Posted by: Count de MonetPlease forgive my ignorance, but what exactly is 'music theory'?

Music Theory is the set of concepts that describes the nature of musical events. It is the process of mentally identifying the sounds that occur in music. We do this in order to build a consistent set of ideas to describe what happens in music.

This tutorial is a brief overview of the most important, fundamental concepts in music theory:

http://www.guitartricks.com/tutorial.php?input=495