A black box theater is a theater with a very simple, unadorned design which makes it an extremely flexible space. These theaters began to proliferate in the 1960s, probably deriving from practice spaces used by major theater companies and universities with large theater programs. Today, numerous black box theaters can be found all over the world, putting on a range of performances from highly experimental theater to Shakespeare.
As its name would suggest, this kind of theater is designed kind of like a box. The room which contains the theater is typically square and painted black, because black is a neutral color which will not clash with costumes, sets, and lighting. The floor is flat and open, allowing people to arrange seating however they desire, and many black box theaters are designed to accommodate risers and platforms to create a raised stage, if desired. Rigging is accomplished on girders overhead which can hold set pieces, lighting, curtains, and so forth.
The great thing about a black box space is that it can be anything anyone wishes to imagine. Other theater spaces can be changed, but their fundamental character remains the same. A black box theater is capable of endless new configurations, allowing people to exercise their creativity, which can be especially valuable in the case of experimental performances, where unusual arrangements of seating and stage may be needed.
These spaces are also inexpensive to construct, which can be very appealing, and some theater companies and many schools have a black box theater in addition to a larger theater, allowing them to hold two productions at once. Black box spaces can also be used for rehearsals, freeing up larger stages for other tasks. The classic black box theater also has a very intimate feel, which appeals to many people, especially actors doing monologues and solo shows, because it allows them to connect with the audience.
Because the space can be used in so many ways, the design of a black box theater focuses heavily on practical measures which will allow the space to be used as desired. The acoustics are typically designed to be excellent, so that the stage can be located anywhere, and the rigging grid, catwalk, or girders is also extremely flexible, to meet the needs of the theater's users. Typically a large storage space is attached for seating, set pieces, and other miscellanea, since the stark space doesn't leave much room for extra items.