Comic opera, also known as light opera, is a type of musical play in which the dialog is mostly spoken, in contrast to grand opera, in which the dialog is entirely or mostly sung. Also, comic opera usually deals with current topics and has a comedic plot with amusing characters and a happy ending, in contrast to grand opera's emphasis on historic and tragic events and its typically fatal endings. Comic operas are often much shorter than grand operas and usually have about fewer acts. Often cast sizes are also much smaller and there are frequently less elaborate scenery, costumes and special effects than in grand operas. These differences allow comic operas to be performed at lower cost and in a wider range of venues.
Comic opera was first appeared in Italy in the late seventeenth century and within decades had evolved into opera buffa as an alternative to conventional opera. It spread to France, where it first became opéra comique and eventually operetta. Although there are some minor differences, particularly with regard to their origins, the terms comic opera and operetta are today frequently used interchangeably because of their similarities and because they greatly influenced each other.