I wrote a bit about music theory with respect to guitars for my brother and decided it was worth sharing.

Scales are a series of notes derived with a set pattern. The root note defines the scale. Let me explain further with two scales that only contain the natural notes (no sharps or flats): A minor and C major. A minor and C major are ‘enharmonic’ meaning they are the same notes;  the difference between the scales is the root note and the pattern that you follow to find the next note. Observe:

A minor scale Notes: A, B, C, D, E, F, G, A Frets on the E string: 5, 7, 8, 10, 12, 13, 15, 17 Pattern (intervals between notes): root, +2, +1, +2, +2, +1, +2, +2 C major scale Notes: C, D, E, F, G, A, B, C Frets on the E string: 8, 10, 12, 13, 15, 17, 19, 20 Pattern (intervals between notes): root, +2, +2, +1, +2, +2, +2, +1

You can play a minor scale by picking the root note then applying the minor pattern: root, +2, +1, +2, +2, +1, +2, +2. In the same way, you can play a major scale by picking a root note then applying the major pattern: root, +2, +2, +1, +2, +2, +2, +1. Another example:

A major scale Notes: A, B, C#, D, E, F#, G#, A Frets on the E string: 5, 7, 9, 10, 12, 14, 16, 17 Pattern (intervals between notes): root, +2, +2, +1, +2, +2, +2, +1

In music theory terms, the +1 difference is called a “half-tone” difference and the +2 is termed a “whole tone.”

If you play notes (mostly) from one scale, you are said to be in that key. For example, if you play notes (mostly) from the E scale, you’re in the key of E (major is generally implied–minor must be stated).

From scales, we can derive chords. Chords are groups of notes. The basic chord is 3 notes: 1 (root), 3, 5 of the scale.

An A minor chord contains the notes A, C, E (1, 3, 5 of the A minor scale).

The C major chord contains C, E, G (1, 3, 5 of the C major scale).

And the A major chord contains A, C#, E (1, 3, 5 of the A major scale).

That’s a quick, high-level overview of the basis of all music. Now, rock on! \m/

If you’re looking for more information, there are some great resources online. One that is nicely chunked is https://www.musictheory.net/lessons