A-flat is a musical note that is one half step lower than the note A. In the context of Western music, it is often represented by the symbol "A♭." This note is commonly used in various musical scales, including the A-flat major scale and the A-flat minor scale, which consist of specific patterns of whole and half steps. In terms of piano keys, A-flat is the black key immediately to the left of the white key A. It plays a significant role in many compositions across different genres, including classical, jazz, and popular music, contributing to the overall harmony and mood of a piece.