Claude Debussy was a French composer who is widely considered to be one of the most influential composers of the late 19th and early 20th centuries. Two of his most famous compositions are 'L'Amer' and 'Etude'. 'L'Amer' is a piece for solo piano that was composed in 1888 and is known for its melancholic and dreamy atmosphere. 'Etude' is a set of twelve pieces for solo piano composed between 1915 and 1917. Both of these works are considered to be masterpieces of Debussy's composition style.