Opéra-ballet
Opéra-ballet is a genre of French Baroque lyric theatre that was most popular during the 18th century, combining elements of opera and ballet, "that grew out of the ballets à entrées of the early seventeenth century". It differed from the more elevated tragédie [en musique] as practised by Jean-Baptiste Lully in several ways. It contained more dance music than the tragédie, and the plots were not necessarily derived from classical mythology and allowed for the comic elements, which Lully had excluded from the tragédie en musique after Thésée. The opéra-ballet consisted of a prologue followed by a number of self-contained acts, often loosely grouped around a single theme. The individual acts could also be performed independently, in which case they were known as actes de ballet.