1. A subject that 75% of "musicians" out there have never touched.
2. An excuse the ignorant make to put down artists that try to push the boundaries of contemporary music. All the while these same ignoramuses believe poor technique and slop equate with good music just because everybody else thinks so. These people also have never bothered to actually listen to the music they loathe so much.
3. A set of (flexible) rules that dictate the manner in which music functions.
In most introductory music theory courses, students learn about the intervallic structure of the major scale and how it is harmonized.
the ESRB rating that stands for Mature, 17+. It basically means it has lots of violence or sex and stuff, and that stores are supposed to check id's when selling the game (unfortunatley, they actually do)