A major is a key of the major family, based on the root note a. The key of A major is written in musical notation with three crosses (f-sharp, c-sharp, g-sharp). The corresponding scale and the fundamental chord of this key (the tonic a-cis-e) are also designated by the term A major.

Vorzeichen A-DurCDEFGAHCDEFGAH

A major is often described as festive, bright and radiant, but see the article Key Character. A major is a particularly suitable key for song accompaniment on the guitar, since the bass notes of the basic A major cadence (d, e, a) correspond to the three lowest - and then empty - strings of the guitar.