Operetta is a form of theatre and a genre of light opera. It includes spoken dialogue, songs, and dances. It is lighter than opera in terms of its music, orchestral size, and length of the work. Apart from its shorter length, the operetta is usually of a light and amusing character. The subject matter may portray "lovers' spats, mistaken identities, sudden reversals of fortune, and glittering parties". It sometimes also includes satirical commentaries.

"Operetta" is the Italian diminutive of "opera" and was used originally to describe a shorter, perhaps less ambitious work than an opera. Operetta provides an alternative to operatic performances in an accessible form targeting a different audience. Operetta became a recognizable form in the mid-19th century in France, and its popularity led to the development of many national styles of operetta. Distinctive styles emerged across countries including Austria-Hungary, Germany, England, Spain, the Philippines, Mexico, Cuba, and the United States. Through the transfer of operetta among different countries, cultural cosmopolitanism emerged in the previous century. Operetta as a genre lost favor in the 1930s and gave way to modern musical theatre. Important operetta composers include Johann Strauss, Jacques Offenbach, Franz Lehár, and Francisco Alonso.