Debussy studied with Guiraud and others at the Paris Conservatoire and as prizewinner went to Rome in 1885, although more important impressions came from his visits to Bayreuth (1888-9) and from hearing Javanese music in Paris in 1889.

Wagner's influence is evident in the cantata La damoiselle elue and the Cinq poemes de Baudelaire, but other songs of the period, notably the settings of Verlaine (Ariettes oubliees, Trois melodies, Fetes galantes, set 1) are in a more capricious style, as are parts of the still somewhat Franckian G minor String Quartet of 1893. In that work he used not only the Phrygian mode but also less standard modes, notably the whole-tone mode, to create the floating harmony he discovered through the work of contemporary writers: Mallarme in the orchestral Prelude a 'L'apres-midi d'un faune' (1894) and Maeterlinck in the opera Pelleas et Melisande. These works also brought forward a fluidity of rhythm and colour quite new to Western music.

Pelleas, with its rule of understatement and deceptively simple declamation, also brought an entirely new tone to opera - but an unrepeatable one. Debussy worked on other opera projects and left substantial sketches for two pieces after tales by Poe (Le diable dans le beffroi and La chute de la maison Usher), but nothing was completed. Instead the main works were orchestral pieces, piano sets and songs.

The orchestral works include the three Nocturnes (1899), characteristic studies of veiled harmony and texture ('Nuages'), exuberant cross-cutting ('Fetes') and seductive whole-tone drift ('Sirenes').

La mer (1905) essays a more symphonic form, with a finale that works themes from the first movement, though the centrepiece ('Jeux de vagues') proceeds much less directly and with more variety of colour. The three Images (1912) are more loosely linked, and the biggest, 'Iberia', is itself a triptych, a medley of Spanish allusions.

Finally the ballet Jeux (1913) contains some of Debussy's strangest harmony and texture in a form that moves freely. Other late stage works, including the ballets Khamma (1912) and La boite a joujoux (1913) and the mystery play Le martyre de St Sebastien (1911), were not completely orchestrated by Debussy, though St Sebastien is remarkable in sustaining an antique modal atmosphere that otherwise was touched only in relatively short piano pieces such as La cathedrale engloutie.

The important piano music begins with works which, Verlaine fashion, look back at rococo decorousness with a modern cynicism and puzzlement (Suite bergamasque, 1890; Pour le piano, 1901). But then, as in the orchestral pieces, Debussy began to associate his music with visual impressions of the East, Spain, landscapes etc, in a sequence of sets of short pieces.

His last volume of Etudes (1915) interprets similar varieties of style and texture purely as pianistic exercises and includes pieces that develop irregular form to an extreme as well as others influenced by the young Stravinsky (a presence too in the suite En blanc et noir for two pianos, 1915). The rarefaction of these works is a feature of the last set of songs, the Trois poemes de Mallarme (1913), and of the Sonata for flute, viola and harp (1915), though the sonata and its companions also recapture the inquisitive Verlainian classicism.

Debussy's planned set of six sonatas was cut short by the composer's death from rectal cancer in 1918.