A 13 chord is an extended dominant chord that adds a richness and complexity to the harmony; its structure builds upon the basic dominant (7th) chord by including the 9th, 11th, and 13th degrees of the scale. However, its most distinctive feature is the addition of the 13th, which is the same as the 6th scale degree an octave higher. This chord is important in jazz and other complex musical genres because it provides a tension that resolves beautifully when used within a progression. Guitarists typically play 13 chords in "drop voicings" to ensure clarity and avoid dissonance due to note crowding. Shapes might omit the 9th or 11th for simplicity. It adds color and depth, often acting as a substitute or enhancement to the standard dominant 7th chord in a progression.