CDEFGABC

CDEFGABC is the contiguous sequence of pitch names that comprises the diatonic scale built on C. In classical music theory, this set of notes corresponds to the C major scale from one C to the next, and is often presented without accidentals because it uses only natural notes on the staff and keyboard. The ascent includes eight notes, with the final C representing the octave of the starting pitch.

The interval pattern of a major scale is whole, whole, half, whole, whole, whole, half. From C to D is a whole step, D to E is a whole step, E to F is a half step, F to G is a whole step, G to A is a whole step, A to B is a whole step, and B to C is a half step. In solfege this corresponds to do re mi fa so la ti do. On a piano, these notes align with the white keys, and the C major key signature is typically shown as having no sharps or flats.

CDEFGABC is often used as a fundamental teaching example for diatonic scales, scale degrees, and melody construction. It represents the C major key, whose relative minor is A minor (the same notes, different tonal center). The concept extends to other tonal centers by transposition, producing different major scales with appropriate accidentals, while the C major set remains a standard reference for beginners and theory discussions.