The Rondo, or Rondeau (Fr.), has its basis in the Baroque Ritornello. It features a repeated section, the Ritornello, that is interspersed with contrasting sections. Representations of the form can be seen in many symphonies, concerti, string quartets, and other works by composers from the Baroque all the way up to modern day.
The form is constructed using a repeated section, Ritornello, that is interspersed with contrasting sections. The most basic rondos feature 3 sections (ABACA; ABACABA) while more complex rondos have been composed with as many as 4 - 5 sections (ABACADABA; ABACADAEABA). The form evolved in the late Classical and Romantic periods to include brief introductions and codas.
- Wolfgang Amadeus Mozart - Sonata in A major, K.331, III.: Rondo alla turca
- Wolfgang Amadeus Mozart - Rondo in A major for Piano and Orchestra
- Joseph Haydn - Gypsy Rondo
- Ludwig van Beethoven - Rondo a Capriccio
- Frederic Chopin - Rondo in C major for two pianos
- Antonin Dvorak - Rondo, Op. 94
A Rondo can be composed in different ways - all dependent on composers intent and overall structural desire. Composers have used many different tools to unite the piece structurally. A good study of the repertoire will provide many instances of various techniques being used in this regard. The most common seen in the works of composers from the classical period is the use of thematic variation or the use of motifs and germs in thematic construction. The simplicity of the form itself has allowed for the merger of other forms into the Rondo with ease. One such example is the merger with Sonata-Allegro form. The merger incorporates the latter forms harmonic plan into the sections of the former (A B (V) A C (vi) A B' (I) A). Other developments include the use of fugal sections, burlesque, and variation. Structurally, Rondos are similar to inventions and scherzos
Dolmetsch Online Music Dictionary 
Rondo and Ritornello Forms in Tonal Music