Theatre or theater is a collaborative form of fine art that uses live performers 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. Elements of art and stagecraft are used to enhance the physicality, presence and immediacy of the experience. The specific place of the performance is also named by the word "theatre" as derived from the Ancient Greek θέατρον (théatron, "a place for viewing"), itself from θεάομαι (theáomai, "to see", "to watch", "to observe").

Theatre studies (sometimes referred to as theatrology or dramatics) is the study of theatrical performance in relation to its literary, physical, psycho-biological, sociological, and historical contexts. It is an interdisciplinary field which also encompasses the study of theatrical aesthetics and semiotics. A late 20th century development in the area has been the ethnographic theory of theatre, pioneered by the Russian scholar Larisa Ivleva (1944-1995) who studied the influence of folk culture on the development of Russian theatre.