Atonality is music without a tonal centre — no single key governs the harmony, freeing the composer from traditional pull and resolution.
Atonality describes music that abandons the system of major and minor keys that organised Western music for roughly three centuries. Around 1908, Arnold Schoenberg in Vienna began composing works — the 'Three Piano Pieces' Op. 11, the song cycle 'Das Buch der hängenden Gärten' — that no longer resolved to a tonic. Anton Webern and Alban Berg, his pupils in what became known as the Second Viennese School, followed. The break with tonality was not nihilistic but liberating: Schoenberg framed it as the 'emancipation of dissonance', the recognition that all twelve notes of the chromatic scale could be treated as equally important. Atonality made possible the expressionist intensity of Berg's 'Wozzeck' (1925), the spare lyricism of Webern, and ultimately Schoenberg's twelve-tone technique. It remains controversial with audiences a century later — but no major 20th-century composer was untouched by it.