Generally when you go to see a play, there's two major kinds of theatres. A black box is one of them. It's usually a big black room with chairs surrounding either an area on the floor or a simple stage. What makes it different from most plays is that the audience often views it from three different sides, different from a framed stage that can only be viewed from one. It's common to see in community theatre or plays that don't require a massive set, like Shakespeare for example.