Guitar chords and harmony are two of the most misunderstood topics on the instrument. Most players learn a handful of open shapes, maybe a few barre chords.
Chord substitutions are one of the most powerful tools a jazz guitarist has. The concept is straightforward: you replace an expected chord with a different one.
Intervals of thirds are one of the most powerful tools in funk rhythm guitar. They sit in a sweet spot: fuller than a single note, but lighter and more mobile than a full chord voicing.