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C-flat (Cb) is the note C lowered by one semitone using a flat (♭). On a piano, C-flat is played on the same key as B, although the two note names have different theoretical meanings.
What is C-flat?
C-flat is an example of enharmonic equivalence, meaning that two differently named notes sound the same in the equal temperament tuning system. While C-flat and B share the same piano key, the name C-flat is used when it fits the harmonic structure of a particular key or chord.
C-flat most commonly appears in keys such as G-flat major and C-flat major, where each letter name must appear only once within the scale.
How is C-flat used in piano playing?
Piano players rarely encounter C-flat in popular music, but it appears more frequently in advanced classical music and jazz. When you see Cb in sheet music or chord symbols, simply play the same key as B while keeping the theoretical spelling in mind.
Understanding C-flat helps pianists read complex key signatures and appreciate how music theory and notation are organized.