Watch the Theory Primer online guitar lesson by Ravi from Guitar Lab: 30 Rock & Pop Progressions
Knowledge is power, so learning the theory behind the creation of music is very valuable to both the writer and player. It is indeed true that many great guitarists and songwriters know very little about music theory, and for that reason I can confidently tell you that you will still get a great deal out of this course even if you skip this section. In fact, I want you to skip this section if it in anyway deters you from moving forward and learning all these fantastic progressions. However, I do encourage you to give it a try and watch this at the beginning, middle, and end of the course. If it doesn't make any sense at first, then you are in the same boat as the rest of us! It should leave you with more questions than answers, because the rest of the course will make it all fall into place. This theory primer is just that, a primer. It is the basics of what I feel you should know to get the most out of the course. As a teacher, I would be doing you a disservice by not including it, but at the same time, I don't want it to get in your way of enjoying the music. Regardless, DOWNLOAD THE ATTACHED GUIDES AND REFER TO THEM THROUGHOUT THE COURSE.
In this segment, I teach the major scale which outlines the notes in each of the 12 major keys. Then, I'll show you how chords are built on each degree of the scale. That teaches you all the chords that exist within a key, which is only seven. In this course, we are really only going to use six, because that is what the vast majority of rock and pop songs use. These six include three major chords and three minor chords. Numerically, they are I-ii-iii-IV-V-vi, which refers to the scale tone upon which each chord is constructed. Chords are written as Roman numerals, with uppercase signifying major chords and lowercase signifying minor chords. The way I like to look at these is the majors (primary chords of a key) I-IV-V and their corresponding relative minors vi-ii-iii. As we breakdown the chord progressions in the course, you will see why this makes sense. The sixth degree of any major chord is its "relative" minor, meaning that the majority of notes in each chord are the same (this is very obvious when fingering the chords on piano, but also visually evident on guitar - such as between C and Am). Therefore, it is common to substitute the I with the vi, and the IV with the ii, and the V with the iii.
I'll also teach you the lay of the land in terms of finding all your root notes on the guitar. This is important, especially for barre chords, since you need to place them on the right fret to get the desired chord. It's not complicated, just remember Before Christ and Elmer Fudd (watch the video for more on that!)
Theory is intimidating at first, but it can also be addictive once you realize how incredibly logical music composition is. It really is a marriage of art and science.