4′33″ is a modernist composition by American experimental composer John Cage. It was composed in 1952 for any instrument or combination of instruments; the score instructs performers not to play their instruments throughout the three movements. It is divided into three movements, lasting 30 seconds, 2 minutes and 23 seconds, and 1 minute and 40 seconds, respectively, although Cage later stated that the movements' durations can be determined by the musician. As suggested by the title, the composition lasts 4 minutes and 33 seconds. It is marked by silence except for ambient sound, which is intended to contribute to the performance.

4′33″ was conceived around 1947–48, while Cage was working on the piano cycle Sonatas and Interludes. Many prior musical pieces were largely composed of silence, and silence played a notable role in his prior work, including Sonatas and Interludes. His studies on Zen Buddhism during the late 1940s about chance music led him to acknowledge the value of silence in providing an opportunity to reflect on one's surroundings and psyche. Recent developments in contemporary art also bolstered Cage's understanding on silence, which he increasingly began to perceive as impossible after Rauschenberg's White Painting was first displayed.

4′33″ premiered in 1952 and was met with shock and widespread controversy; many musicologists revisited the very definition of music and questioned whether Cage's work qualified as such. Cage intended 4′33″ to be experimental—to test the audience's attitude to silence and prove that any auditory experience may constitute music, seeing that absolute silence cannot exist. Although 4′33″ is labelled as four minutes and thirty-three seconds of silence, Cage maintains that the ambient noises heard during the performance contribute to the composition. Since this counters the conventional involvement of harmony and melody in music, many musicologists consider 4′33″ to be the birth of noise music, and some have likened it to Dadaist art. 4′33″ also embodies the idea of musical indeterminacy, as the silence is subject to the individual's interpretation; thereby, one is encouraged to explore their surroundings and themselves.

4′33″ greatly influenced modernist music, furthering the genres of noise music and silent music, which—whilst still controversial to this day—reverberate among many contemporary musicians. Cage re-explored the idea of silent composition in two later renditions: 0′00″ (1962) and One³ (1989). In a 1982 interview, and on numerous other occasions, he stated that 4′33″ was his most important work. The New Grove Dictionary of Music and Musicians describes 4′33″ as Cage's "most famous and controversial creation". In 2013, Dale Eisinger of Complex ranked the composition eighth in his list of the greatest performance art works.

The first time Cage mentioned the idea of a piece composed entirely of silence was during a 1947 (or 1948) lecture at Vassar College, A Composer's Confessions. At this time, he was working on the cycle for piano Sonatas and Interludes. Cage told the audience that he had "several new desires", one of which was:

to compose a piece of uninterrupted silence and sell it to Muzak Co. It will be three or four-and-a-half minutes long—those being the standard lengths of "canned" music and its title will be Silent Prayer. It will open with a single idea which I will attempt to make as seductive as the color and shape and fragrance of a flower. The ending will approach imperceptibility.

Prior to this, silence had played a major role in several of Cage's works composed before 4′33″. The Duet for Two Flutes (1934), composed when Cage was 22, opens with silence, and silence was an important structural element in some of the Sonatas and Interludes (1946–48), Music of Changes (1951) and Two Pastorales (1951). The Concerto for prepared piano and orchestra (1951) closes with an extended silence, and Waiting (1952), a piano piece composed just a few months before 4′33″, consists of long silences framing a single, short ostinato pattern. Furthermore, in his songs The Wonderful Widow of Eighteen Springs (1942) and A Flower (1950) Cage directs the pianist to play a closed instrument, which may be understood as a metaphor of silence.

However, at the time of its conception, Cage felt that a fully silent piece would be incomprehensible, and was reluctant to write it down: "I didn't wish it to appear, even to me, as something easy to do or as a joke. I wanted to mean it utterly and be able to live with it." Painter Alfred Leslie recalls Cage presenting a "one-minute-of-silence talk" in front of a window during the late 1940s, while visiting Studio 35 at New York University.