Claude Debussy Claire de Lune What are the main keys and key signature What is the structure or form?

Claude Debussy's "Clair de Lune" is primarily in the key of D-flat major, with sections that modulate to related keys such as C-sharp minor. The piece features a 3-part ternary form (ABA), where the first section presents a lyrical theme, the middle section contrasts with a more intense and dynamic passage, and the final section returns to the serene character of the opening, creating a cohesive and flowing musical narrative. The key signature reflects the lush harmonies characteristic of Debussy's impressionistic style.