D-flat is a musical note that is one half step lower than D and one half step higher than C. In the context of a piano, it is played by pressing the black key immediately to the left of D. D-flat is often used in various musical scales and chords, contributing to the overall harmony of a piece. In terms of musical notation, D-flat is represented by the symbol "♭" placed before the note D. It is commonly found in compositions written in the key of D-flat major or B-flat minor, which are popular in classical and jazz music.