learning music theory

I don't know the answers to the questions! How do I learn this?
If you you have a teacher or professor to teach you what you need to know, that's great. If you're on your own (or if you just want some extra tips), there are still a lot of very good websites that will help you learn what you need to know, for free (see below).

Coming soon -- more links, better organization, and descriptions of what you will find on each of these websites. I will also be working on a list of good non-free music theory resources online.

How to read sheet music - good basic tutorial at NotationMachine.com
Intro to reading music - also see other resources at datadragon.com
Standard music notation - reading music, especially for guitarists at Wolfmans.com
BeginBand.com - for students starting out in band and orchestra
Music Theory Online - in-depth theory reference
MusicTheory.net - interactive lessons and trainers
Teoría - interactive exercises, references
BigEars - interactive ear trainer
Fundamentals of Piano Practice, 2nd Edition - piano lessons and teaching material
Basic Music Theory textbook - free downloadable book
Gary Ewer's Easy Music Theory (free lessons at bottom of page)
Jazz Guitar Online - music theory lessons and other resources especially for jazz guitarists