Ab Major is a musical key that consists of the notes Ab, Bb, C, Db, Eb, F, and G. It is characterized by its warm and rich sound, often used in various genres, including classical, jazz, and pop music. The key signature of Ab Major has four flats, which are Bb, Eb, Ab, and Db. In terms of its scale, Ab Major is the relative major of F minor, meaning they share the same key signature but have different tonal centers. Composers like Ludwig van Beethoven and Johannes Brahms have utilized Ab Major in their works, showcasing its expressive qualities.