John Cage was an American composer and music theorist. He was a pioneer in the implementation of indeterminacy in music, as well as in his use of non-standard musical instruments and electroacoustic ways of generating sound. He was one of the leading composers of the 20th century and propelled the post war avant-garde movement. His teachers included Henry Cowell and Arnold Schoenberg, both known for their radical innovations in music, but Cage's major influences lay in various East and South Asian cultures. Through his studies of Indian philosophy and Zen Buddhism in the late 1940s, Cage came to the idea of aleatoric or chance-controlled music, which he started composing in 1951.
Cage is perhaps best known composition 4′33″ (1952), which is performed in the absence of deliberate sound; musicians who present the work do nothing aside from being present for the duration specified by the title. The content of the composition is not "four minutes and 33 seconds of silence," as is often assumed, but rather the sounds of the environment heard by the audience during performance. The work's challenge to assumed definitions about musicianship and musical experience made it a popular and controversial topic both in musicology and the broader aesthetics of art and performance. Cage was also a pioneer of the prepared piano (a piano with its sound altered by objects placed between or on its strings or hammers), for which he wrote numerous dance-related works and a few concert pieces.