Opera is a form of theatre in which music is a fundamental component and dramatic roles are taken by singers. Such a "work" is typically a collaboration between a composer and a librettist and incorporates a number of the performing arts, such as acting, scenery, costume, and sometimes dance or ballet. The performance is typically given in an opera house, accompanied by an orchestra or smaller musical ensemble, which since the early 19th century has been led by a conductor. Although musical theatre is closely related to opera, the two are considered to be distinct from one another.

Theatre or theater is a collaborative form of performing art that uses live performers, usually actors or actresses, to present the experience of a real or imagined event before a live audience in a specific place, often a stage. The performers may communicate this experience to the audience through combinations of gesture, speech, song, music, and dance. It is the oldest form of drama, though live theatre has now been joined by modern recorded forms. Elements of art, such as painted scenery and stagecraft such as lighting are used to enhance the physicality, presence and immediacy of the experience. Places, normally buildings, where performances regularly take place are also called "theatres", as derived from the Ancient Greek θέατρον, itself from θεάομαι.