A-flat is a musical note that is one half step lower than the note A. In the context of the piano, it is played by pressing the black key immediately to the left of the A key. A-flat is often used in various musical scales and chords, contributing to the overall harmony of a piece. In Western music, A-flat can be represented in different ways, such as in the A-flat major scale or the A-flat minor scale. It is also commonly found in compositions by famous composers like Ludwig van Beethoven and Johann Sebastian Bach, adding depth and emotion to their works.