CMAJ

Cmaj denotes the musical key of C major in Western tonal music, or the C major triad when context indicates a chord. The C major scale consists of the notes C, D, E, F, G, A and B, returning to C. In written music, C major is characterized by a key signature with no sharps or flats.

In the diatonic system, C major is the tonic key with a set of seven diatonic chords: I is C major (C–E–G), II is D minor (D–F–A), III is E minor (E–G–B), IV is F major (F–A–C), V is G major (G–B–D), VI is A minor (A–C–E), and VII is B diminished (B–D–F). Common progressions in this key include I–IV–V–I and ii–V–I, as well as I–vi–ii–V in many pop and jazz tunes.

The C major chord itself is a triad built from C, E, and G. Variations frequently encountered in sheet music include Cmaj7 (C–E–G–B), Cadd9 (C–E–G–D), and C6 (C–E–G–A). In practice, the symbol C generally implies a C major triad unless the context specifies a different quality, such as C minor or C diminished, or an explicit modifier like Cmaj7.

C major is widely used as a reference key in music education and composition because its lack of sharps or flats simplifies fingering and theoretical demonstrations. It is common across classical, folk, and popular music and serves as a foundational key for beginners.