The Grand Staff is a musical notation system used in Western music to represent pitches. It consists of two staves: the upper staff, which typically uses the treble clef, and the lower staff, which uses the bass clef. The two staves are connected by a vertical line on the left, allowing musicians to read both treble and bass notes simultaneously. This system is essential for notating music for instruments like the piano, where both hands play different parts. The Grand Staff helps musicians understand the relationship between notes and their corresponding pitches, facilitating easier reading and performance of complex compositions.