The Major Thirteenth Chord extends the Major Seventh Chord by adding a major ninth, a perfect eleventh (often omitted or altered), and a major thirteenth. The theoretical notes are: root, major third, perfect fifth, major seventh, major ninth, perfect eleventh, and major thirteenth. It is an extremely rich and dense chord, with a lush, dreamy, and deeply 'jazzy' sound. On guitar, the fifth and eleventh (especially the natural eleventh, which would create a strong dissonance with the major third) are almost always omitted in practical voicings to obtain clean and functional voicings. When the eleventh is present, it is almost always augmented (#11) to avoid dissonance with the major third, giving the chord a 'Lydian' color (Maj7#11). The thirteenth adds an 'airy' and melodic note, completing the voicing with a sense of fullness and sophistication. It is typically used on tonic (I) or subdominant (IV) chords to add a sophisticated and layered harmonic color.