A quodlibet is a piece of music combining several different melodies, usually popular tunes, in counterpoint and often a light-hearted, humorous manner. The term is Latin, meaning "whatever" or literally, "what pleases." There are three main types of quodlibet:

The origins of the quodlibet can be traced to the 15th century, when the practice of combining folk tunes was popular. Composer Wolfgang Schmeltzl first used the term in a specifically musical context in 1544. An early exponent of the genre was 16th century composer Ludwig Senfl whose ability to juxtapose several pre-existing melodies in a cantus firmus quodlibet resulted in works such as Ach Elselein/Es taget, a piece noted for its symbolism rather than its humor. Even earlier we can find another example in Francisco de Peñalosa's Por las sierras de Madrid, from his Cancionero Musical de Palacio. However, it was Praetorius who, in 1618, provided the first systematic definition of the quodlibet as "a mixture of diverse elements quoted from sacred and secular compositions".^{[citation needed]} During the Renaissance, a composer's ability to juxtapose several pre-existing melodies, such as in the cantus firmus quodlibet, was considered the ultimate mastery of counterpoint.

John Milton Cage Jr. (September 5, 1912 – August 12, 1992) was an American composer, music theorist, writer, and artist. A pioneer of indeterminacy in music, electroacoustic music, and non-standard use of musical instruments, Cage was one of the leading figures of the post-war avant-garde. Critics have lauded him as one of the most influential American composers of the 20th century. He was also instrumental in the development of modern dance, mostly through his association with choreographer Merce Cunningham, who was also Cage's romantic partner for most of their lives.

Cage is perhaps best known for his 1952 composition 4′33″, 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 sometimes 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. The best known of these is Sonatas and Interludes (1946–48).