Atonal music that is music that is written and performed without regard to any specific key or tonal center (see tonality). Atonality in Western music was first used famously in 1908 by Arnold Schoenberg in the middle of his second string quartet. Schoenberg preferred the term "pantonality", since atonality seemed to imply an anti-musical process. Atonal passages are also found in Stravinsky's Rite of Spring, Prokofiev's first piano concerto, and Skryabin's piano music.
Schoenberg's twelve-tone row
Schoenberg worked at getting rid of traditional harmony, especially the tonal center, by adopting a twelve-tone row. Each of his compositions was based on a series or row made of all twelve chromatic tones arranged in a specific order. The order of the row stays the same throughout the work, but may be varied by transposing it by octaves, changing the rhythm, or using the row backwards.