Rondo

A form based on the principle of periodic thematic return. Typically rondo movements are light and engaging and occur as the last movement in a Classical sonata or Concerto. The meter is usually duple and the tempo is usually presto. The idea of departure and return is expanded in the rondo and the internal structure can be diagrammed:

A  B  A  C  A  D  A  (coda)

The rondo theme is catchy and remember able because you are going to have to remember it when it comes back. The thematic material of the contrasting sections is usually filler music as to not compete with the tuneful rondo theme. The form goes like this: theme-something different-theme-something different-theme something different-theme and then inevitably a coda to tell you there are no more contrasts.