G Major 7th
maj7
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About G Major 7th
G major seventh is a G with the F♯ added, and on guitar it is one of those chords whose easiest form is nearly accidental: fret the standard G, then move one finger, and the seventh appears on the high E string. It is the sound of a song that has stopped moving on purpose.
The notes
G, B, D, F♯. The F♯ is a semitone below the octave G, and that half step is the whole character of the chord — present, slightly astringent, and in no hurry.
Lower the F♯ to F and you have G7, which pulls hard toward C. The two chords look almost identical on paper and behave in opposite ways, which makes them the clearest pair for hearing what a major seventh actually does.
Voicings
The common open shape frets the low G and B and leaves the high strings ringing, with the F♯ on the high E at the second fret. A fuller version adds the fifth on the B string.
Barred at the third fret with the root on the low E, the same chord becomes movable — that shape is what jazz uses, because the open version cannot be altered or voiced-led.
Where it shows up
As the I of G major and the IV of D. Both are guitar keys, so the chord turns up in a great deal of acoustic writing where a plain G would sound too settled.
In jazz it closes the ii–V–I in G: Am7, D7, Gmaj7. That progression is to the guitar what the same cadence in C is to the piano — the default place to start.