A# minor is a minor scale based on the note A#. It consists of the notes A#, C#, D#, E#, F#, G#, and A#. This scale is often used in various music genres, providing a somber and introspective sound. In terms of its key signature, A# minor has seven sharps, making it one of the more complex keys to play on instruments like the piano. It is the relative minor of the key of C# major, sharing the same key signature but offering a different emotional quality in compositions.