A major seventh chord is a four-note chord, which consists of four notes: the root, the major third, the perfect fifth, and the major seventh.
The formula 1-3-5-7 represents the intervallic structure of a major seventh chord:
For example, in a C major seventh chord:
The combination of these four notes (C, E, G, B) creates the sound of a C major seventh chord.
A major seventh chord has a lush and sophisticated quality due to the presence of the major seventh interval. This chord is often associated with a dreamy or jazzy sound and is used to add color and complexity to music.
On a piano or keyboard, major seventh chords are typically played by pressing the root note, the major third, the perfect fifth, and the major seventh.
In guitar playing, major seventh chords are formed by pressing down specific combinations of strings and frets, following chord diagrams or finger positions.