A theater or theatre is a structure where theatrical works or plays are performed or other performances such as musical concerts may be given. While a theater is not required for performance (as in environmental theater or street theater), a theater serves to define the acting and audience spaces and organize the theater space as well as provide facilities for the performers, the technical crew and the audience.
There are as many types of theaters as there are types of performance. Theaters may be built specifically for a certain types of productions, they may serve for more general performance needs or they may be adapted or converted for use as a theater. They may range from open-air amphitheaters to ornate, cathedral-like structures to simple, undecorated rooms or black box theaters. Some theaters may have a fixed acting area (in most theaters this is known as the stage), while some theaters such as black box theaters, may not, allowing the director and designers to construct an acting area suitable for the production.
The most important of these areas is the acting space generally known as the stage. In some theaters, specifically proscenium theaters, arena theaters and amphitheaters, this area is permanent part of the structure. In a blackbox theater, the acting area is undefined so that each theater may adapt specifically to a production.
In addition to these acting spaces, there may be offstage spaces as well. These include wings on either side of a proscenium stage (called "backstage" or "offstage") where props, sets and scenery may be stored as well as a place for actors awaiting an entrance. A Prompter's box may be found backstage. In an amphitheater, an area behind the stage may be designated for such uses while a blackbox theater may have spaces outside of the actual theater designated for such uses.
Often a theater will incorporate other spaces intended for the performers and other personnel. A booth facing the stage may be incorporated into the house where lighting and sound personnel may view the show and run their respective instruments. Other rooms in the building may be used for dressing rooms, rehearsal rooms, spaces for constructing sets, props and costumes, as well as storage.
All theaters provide a space for their audience. The audience are usually separated from the performers by the proscenium arch; in such proscenium theaters and amphitheaters, these areas, like the stage, are a permanent feature of the structure. This area is known as the auditorium or the house. Like the stage in a blackbox theater, this area is also defined by the production.
The seating areas can include some or all of the following:
In addition, many theaters may provide areas specifically designated for the comfort of the audience. These areas include a lobby where tickets and concessions may be sold at the box office, restrooms, and other areas where the audience may relax before, in between or after performances. These areas may be known as the "Front of House" or FOH.
The centrepiece of the theater was the orchestra, or "dancing place", a large circular or rectangular area. The orchestra was the site the choral performances, the religious rites, and, possibly, the acting. An altar was located in the middle of the orchestra; in Athens, the altar was dedicated to Dionysus.
Behind the orchestra was a large rectangular building called the skene (meaning "tent" or "hut"). It was used as a "backstage" area where actors could change their costumes and masks, but also served to represent the location of the plays, which were usually set in front of a palace or house. Typically, there were two or three doors in the skene that led out onto orchestra, and from which actors could enter and exit. At first, the skene was literally a tent or hut, put up for the religious festival and taken down when it was finished. Later, the skene became a permanent stone structure. These structures were sometimes painted to serve as backdrops, hence the English word scenery.
In front of the skene there may have been a raised acting area called the proskenian, the ancestor of the modern proscenium stage. It is possible that the actors (as opposed to the chorus) acted entirely on the proskenian, but this is not certain.
Rising from the circle of the orchestra was the audience. The audience sat on tiers of benches built up on the side of a hill. Greek theaters, then, could only be built on hills that were correctly shaped. A typical theater was enormous, able to seat around 15,000 viewers.
Greek theaters were not enclosed; the audience could see each other and the surrounding countryside as well as the actors and chorus.
See also: Theater of Ancient Greece
Around this time, the green room, a place for actors to wait until required on stage, became common terminology in English theaters.
The Globe has now been rebuilt as a fully working and producing theater near its original site (largely thanks to the efforts of film director Sam Wanamaker) to give modern audiences an idea of the environment for which Shakespeare and other playwrights of the period were writing.
Specific designs of contemporary live theaters include proscenium, thrust, black box theater, theater in the round, amphitheater, and arena. In the classical Indian dance, Natya Shastra defines three stage types. In Australia and New Zealand a small and simple theater, particularly one contained within a larger venue, is a theatrette. The word originated in 1920s London, for a small-scale music venue.
Theatrical performances can also take place in venues adapted from other purposes, such as train carriages. In recent years the Edinburgh Fringe has seen performances in a lift (elevator) and a taxi.