If you want to play the guitar or write songs you will need to know something, at least, about guitar music theory. You could break down guitar theory down to the study of three elements: chords, scales and arpeggios.

Scales come easily to some people but others find them difficult to learn and difficult to understand. You can, in fact, relate scales to chord shapes. Understanding chords and scales is a matter of exploring the relationships between the notes on the guitar fretboard, but it is not necessary to learn to read music, just find the patterns on the guitar neck.

When you look at scales you will see a symbol like: # or b. The # is the sharp symbol which indicates when a note is played one fret above where it would normally be played. The b symbol is called a flat which is when the note is played a fret lower. One fret on the guitar is called a half step as opposed to a whole step or whole note. In the musical scale there is only a half step between the notes B and C and the notes E and F. The notes that don't have a sharp or flat symbol are called "naturals".

The complete set of notes in the octave are, in alphabetical order, A A# B C C# D D# E F F# G G#. So these notes as they are played in the C scale are C C# D D# E F F# G G# A A# B. The notes on the guitar begin with the open sixth string which sounds the note E, then going up the frets, F G A B C finishing the first octave on the open fourth string D. The octaves continue for twenty-one frets on most electric guitars and nineteen frets for acoustic guitars that don't have a cutaway body.

Chords contain three or more notes. These notes form part of a scale that has the same name as the chord. The E major chord, for example, has three notes from the E major scale. Not all notes are created equal. The most important notes in a chord are the third and the seventh. They tell us whether the chord is major, minor or dominant.

When you play chords in a particular order it is called a progression. Most chord progressions in popular music are based on the first, fourth and fifth notes of a scale. The twelve bar blues progression is one of the most popular chord progressions. Here is a how it works out in the key of C: you are using the first note - C, the fourth, F and the fifth, G. You play four bars using the C chord, two using F, the next two bars you play C again and the next two are G and F, finishing with two bars of the C chord. The most obvious example of this progression put into practice is the instrumental piece called Guitar Boogie.