An oratorio is a large musical composition for orchestra, choir, and soloists, usually on a sacred or religious subject. It is performed in churches and concert halls, and the story is told through the music, without the use of scenery, costumes, and action. An oratorio includes the use of a choir, soloists, an instrumental ensemble, various distinguishable characters, and arias. However, unlike opera, oratorio is strictly a concert piece, and there is generally little or no interaction between the characters, and no props or elaborate costumes. The choir often plays a central role in an oratorio. The text of an oratorio is usually based on scripture, and the narration necessary to move from scene to scene is supplied by recitatives sung by various voices to prepare the way for airs and choruses.

Oratorios became extremely popular in early seventeenth-century Italy partly because of the success of opera and the Catholic Churchs prohibition of spectacles during Lent. Oratorios became the main choice of music during that period for opera audiences. The term oratorio derives from the oratory of the Roman church in which, in the mid-16th century, St. Philip Neri instituted moral musical entertainments, which were divided by a sermon, hence the two-act form common in early Italian oratorio. The principal schools of oratorios are the Italian, essentially a form of religious opera; the German, developed from treatment of the Passion story; and the English, synthesized by the composer George Frideric Handel from several forms.