Watch the Chord Scales online guitar lesson by Jennifer Batten from Rock Sauce for Rhythm Guitar
Chord scales are derived from diatonic scales. There are only 3 types of chords; major, minor and dominant. Any chord name you’ll ever find, will fall into one of those 3 categories. Once you understand the order and types of chords in a chord scale, you can then decipher what key any given progression is in, and thus know what scales to play over the chords when soloing. This knowledge will also help you choose chord progressions that make sense when you're composing.