A chord is really just three notes stacked together — the 1, the 3, and the 5. The 1 is the "root": the note the chord is named after (the root of a C chord is the note C). Stack the 3rd and 5th on top of it and you've got a chord — that's the minimum it takes to make one. This tool lights those three notes up all over the neck and circles the shapes you can actually grab.

The same chord can be played in five different spots up and down the neck, using five shapes named after open chords you may already know (C, A, G, E, D). This shows all five and how they link together — so one chord isn't stuck in one place.

The pentatonic is a five-note scale — the one most people use to solo. It lives in box shapes you slide around the neck. The neat part: each box is really just a chord (those same 1-3-5 notes) with two extra notes added. Turn the extras off and the chord appears inside.