The rondo is a musical form that contains a principal theme (sometimes called the "refrain") which alternates with one or more contrasting themes, generally called "episodes", but also occasionally referred to as "digressions" or "couplets". Some possible patterns include: ABACA, ABACAB, ABACBA, or ABACABA.

The rondo form emerged in the Baroque period and became increasingly popular during the Classical period. The earliest examples of compositions employing rondo form are found within Italian opera arias and choruses of the first years of the 17th century. These examples use a multi-couplet rondo or chain rondo (ABACAD) known as the Italian rondo.

Rondo form, also known in English by its French spelling rondeau, should not to be confused with the unrelated and similarly named forme fixe rondeau; a 14th- and 15th-century French poetic and chanson form. While the origins of rondo form come from Italian opera, the French composer Jean-Baptiste Lully, who is sometimes referred to as the father of the rondo or rondeau form, and his contemporaries, Jacques Champion de Chambonnières and Louis Couperin popularized the rondo form in France in the 17th century. These composers were succeeded in the later Baroque period by French composers Jean-Marie Leclair, François Couperin, and most importantly Jean-Philippe Rameau who continued to be important exponents of music compositions utilizing rondo form. Lully was the first composer to utilize a two-couplet design to his rondo structure, a technique he did not consistently adopt but which was later adopted and standardized by Rameau whose construction of the rondo was codified by the 17th century music theorist Jean Du Breuil in what became known as the French rondeau.

These French composers employed rondo form in a wide range of media, including opera, ballet, choral music, art songs, orchestral music, chamber music, and works for solo instrument. The French spread the popularity of the form internationally, and the rondo was soon adopted in the late 17th century and early 18th century by composers in other nations such as Henry Purcell in England and Johann Sebastian Bach in Germany. While J.S. Bach's rondos were written in the earlier French tradition of construction and were not particularly progressive, his son Carl Philipp Emanuel Bach was a highly imaginative and unusually innovative composer in the rondo form; producing thirteen sophisticated and highly personal rondos which place him as a central figure in this form at the end of the Baroque period and early Classical period.

By the beginning of the Classical period in 1750, the rondo form was already well established throughout Europe and the rondo form reached the height of its popularity in the late 18th century. During this period the rondo form was most frequently employed by composers as a single movement within a larger work; particularly concertos and serenades but also with less frequency in symphonies and chamber music. However, independent rondos were still written in this period, often as virtuoso pieces. Many European composers of this era used the rondo form, including the composers Joseph Haydn, Wolfgang Amadeus Mozart and Ludwig van Beethoven who all produced a significant body of music employing rondo form. These three composers were also important exponents of the sonata rondo form; a musical form developed in the Classical period which blended the structures of the sonata form with the form of the rondo.

In the 19th century composers in the Romantic period continued to use the form with some regularity. Some Romantic era composers to produce music utilizing rondo form include Beethoven, Johannes Brahms, Antonín Dvořák, Felix Mendelssohn, Franz Schubert, Robert Schumann, Richard Strauss, and Pyotr Ilyich Tchaikovsky. Rondo form has continued to be used by some 20th-century and 21st-century composers; most often by those with a Neoclassical aesthetic or by those composers referencing classical music composition in some fashion. Some 20th century composers to utilize rondo form include Alban Berg, Béla Bartók, Duke Ellington, Alberto Ginastera, Paul Hindemith, and Sergei Prokofiev.