Major scale is made up of a major 2nd, major 3rd, perfect 4th, perfect 5th, major 6th, and major 7th. Major scale with a minor 3rd is Melodic Minor Major scale with a minor 3rd and a minor 6th is Harmonic Minor Major scale with a minor 3rd, a minor 6th, and a Minor 7th is the relative minor Major scale with a minor 3rd and minor 7th is the Dorian mode Major scale with a minor 7th is the Mixolydian mode Major scale with a flat 4 is the Lydian mode You get the idea ... EVERYTHING is relatable to the major scale. If you can master intervals on the fretboard, you can easily build every/any chord, play any arpeggio, and move through any scale and never hit a sour note.