The Gadd9 chord, also known as G suspended 2nd, is a musical chord that consists of the notes G, A, and D. It is formed by taking a standard G major chord and adding the second note of the G major scale, which is A. This creates a unique sound that adds tension and color to music, making it popular in various genres. In guitar playing, the Gadd9 chord can be played by placing fingers on specific frets to achieve the desired notes. It is often used in pop, rock, and jazz music, providing a fresh alternative to traditional major chords.