Theatre is a collaborative form of fine art
Fine art
Fine art or the fine arts encompass art forms developed primarily for aesthetics and/or concept rather than practical application. Art is often a synonym for fine art, as employed in the term "art gallery"....

 that uses live performers to present the experience of a real or imagined event before a live audience in a specific place. The performers may communicate this experience to the audience through combinations of gesture, speech, song, music or dance. Elements of design and stagecraft
Stagecraft is a generic term referring to the technical aspects of theatrical, film, and video production. It includes, but is not limited to, constructing and rigging scenery, hanging and focusing of lighting, design and procurement of costumes, makeup, procurement of props, stage management, and...

 are used to enhance the physicality, presence and immediacy of the experience.

All the world's a stage / And all the men and women merely players / They have their exits and their entrances / And one man in his time plays many parts ...

William Shakespeare, "All the world's a stage|All the world's a stage", As You Like It, Jaques (Act II, Scene VII, lines 139-166)

By increasing the size of the keyhole, today's playwrights are in danger of doing away with the door.

Peter Ustinov, Christian Science Monitor, (1962) - reported in Colin Jarman (1993). The Book of Poisonous Quotes. McGraw-Hill Professional, p. 104. ISBN 0809236818.