The Thirteenth Chord is a complex musical chord that includes the root, third, fifth, seventh, ninth, and thirteenth notes of a scale. It is often used in jazz and contemporary music to create rich, layered harmonies. The chord can be built on various root notes, allowing for a wide range of tonal possibilities. In music theory, the thirteenth chord is typically notated as a dominant seventh chord with an added thirteenth. For example, a C13 chord includes the notes C, E, G, Bb, D, and A. This chord adds depth and color to compositions, making it a favorite among musicians and composers.