B-flat is a musical note that is one semitone lower than B and one semitone higher than A. It is commonly used in various musical scales and is represented by the symbol "B♭" in sheet music. B-flat is a fundamental note in many instruments, including the trumpet, saxophone, and piano. In the context of music theory, B-flat can serve as a tonic in the B-flat major and B-flat minor scales. These scales are often used in genres like jazz, classical, and blues. The note plays a crucial role in creating harmony and melody in compositions.