D major is a major chord made of 3 notes: D, F♯, A. It sounds bright, settled and complete, and you hear it in the home chord of countless songs in every style. It is the I chord of D major and turns up in 5 other keys.
The library above opens on D with 14 shapes up and down the neck, starting with hand-checked ones. Tap a shape to hear it, or play it one string at a time.