A theatre is a building where actors perform plays, musicals, and other live performances for an audience. Unlike watching a movie on a screen, theatre puts real people on stage right in front of you, speaking their lines and acting out stories as you watch. The word comes from ancient Greek, where crowds gathered in outdoor amphitheatres to watch plays performed as part of religious festivals.

A theatre usually has rows of seats facing a stage, along with backstage areas where actors prepare, change costumes, and wait for their entrances. The stage might have curtains, special lighting, and scenery that helps create different worlds, like a forest, a palace, or a city street. Some theatres are enormous and grand, with hundreds of seats and ornate decorations. Others are small and intimate, where the audience sits just feet away from the performers.

Theatre also refers to the art form itself: the work of writing, directing, and performing plays. When someone says they love theatre, they mean they enjoy live performance as an art. People who work in theatre might be actors, directors, set designers, or playwrights (people who write plays).

The British spelling is theatre, while Americans often write theater, though both spellings appear in the United States.