Chromatic Scale - In equal temperament the chromatic scale is made up of all 12 semi-tones and the octave. Originally, it was a Pythagorean scale made of a series of eleven 3:2 perfect fifths - but that is all a bit academic now. The chromatic scale is a term you can understand these days to mean all the notes on the fretboard.

Diatonic Scale - The diatonic scale is a seven note scale (aka heptatonic scale is Greek for '7 notes') across the 12 semitone steps spanning octaves. However in a diatonic scale there are 5 whole-tone steps and 2 half-tone steps to make the numbers of notes equal seven. To make the scale sound smooth the half-tone steps are spread out as far apart from each other in the sequence as possible, resulting in several possible variations of diatonic scales, called modes.

Pentatonic Scale - A pentatonic scale is made up of five notes per octave. Pentatonic scales are common in folk-inspired and ethnic musical traditions, including American Blues and Rock.