Listen up: scales aren’t just torture devices invented by guitar teachers... When you use a scale, say, C major, you are playing ‘in the key of C’. The word ‘diatonic ... F chord shown here.

5 simple music theory hacks to make your tracks stand out ... The Ab7 is a jazzy substitution for a D7 chord (D7 would be diatonic: D F# A C). Total Guitar is Europe's best-selling guitar magazine.