musical-dramatic production similar in structure to a light opera but characteristically having a romantically sentimental plot interspersed with songs, orchestral music, and rather elaborate dancing scenes, along with spoken dialogue.

The operetta originated in part with the tradition of popular theatrical genres such as the commedia dell'arte (commedia erudita) that flourished in Italy from the 16th to the 18th century, the vaudeville of France, and English ballad opera. In the 19th century the term operetta came to designate stage plays with music that were generally of a farcical and satiric nature. The most successful practitioner of this art was Jacques Offenbach (Offenbach, Jacques), whose Orphée aux enfers (1858; Orpheus in the Underworld) and La Belle Hélène (1864; “The Beautiful Helen”) used the guise of Greek mythology to express a satiric commentary on contemporary Parisian life and mores. In England, from the late 1870s, the team of W.S. Gilbert (Gilbert, Sir W.S.) and Arthur Sullivan (Sullivan, Sir Arthur), influenced by Offenbach's works, established their own part in the genre with a large body of works, the best-known of which include H.M.S. Pinafore (1878), The Pirates of Penzance (1879), The Mikado (1885), and Iolanthe (1882).

In Vienna about 1870, Johann Strauss the Younger (Strauss, Johann, The Younger) was producing operettas of a more romantic and melodious type, such as Die Fledermaus (1874; The Bat), which in many respects reconciled the differences between operetta and opera. Toward the end of the 19th century, perhaps influenced by the gentler quality of Viennese operetta, the French style became more sentimental and less satiric, stressing elegance over parodic bite. Viennese successors to Strauss, such as Franz Lehár (Lehár, Franz) (Hungarian by birth), Oscar Straus (Straus, Oscar), and Leo Fall, and French composers such as André Messager (Messager, André) contributed to the evolution of operetta into what is now called musical comedy (see musical).

The operetta traditions of Austria, France, Italy, and England began to wane in the early 20th century but found new life in the United States in the works of Reginald De Koven (De Koven, Reginald) (Robin Hood, 1890), John Philip Sousa (Sousa, John Philip) (El Capitan, 1896), Victor Herbert (Herbert, Victor) (Babes in Toyland, 1903), and Sigmund Romberg (Romberg, Sigmund) (The Student Prince, 1924; The Desert Song, 1926). In the United States the development of jazz accelerated the transition from operetta to musical comedy.