Claude Debussy was a French composer who is widely regarded as one of the most influential composers of the late 19th and early 20th centuries. He is best known for his compositions 'La Mer' and 'Clair de Lune'. Debussy's music is noted for its sensory content and frequent usage of atonality. He was also one of the first composers to make use of whole-tone scales, pentatonic scales, and modes in unconventional ways. Debussy's works are often described as impressionistic, although he rejected the term. He is also credited with pioneering the use of orchestral color and harmony.