what makes a stage space

The simplest form of stage is an empty space. However, this can be developed by the introduction of Rostrums. Rostrums are blocks, made of solid materials, that are of different heights, widths, lengths and shapes that are used to break up an acting space into different levels. Groups of Rostrums can be put together to make a raised stage.

Sets are the bits and pieces of different material that are used to give the illusion that the performance is set somewhere other than the theatre. Sometimes called Scenery, the sets "set" or establish the scene. Different furnishings (for example, tables, chairs and beds) can be classed as sets, as well as, the structure in which the furnishings are housed.

Properties or Props are personal items that an actor uses on stage as part of the performance. These include things like suitcases and bags, a hairbrush, papers and pens, reading glasses, drinking glasses and anything else that is of a small nature. 

The props are usually kept on the Props Table in the wings. It is important that the actors remember to collect their props before the scene and return them to the table when they come off the stage, to ensure that the props are ready for the next performance.

A Flat is a unitary section of flat scenery, sometimes painted to give the impression of a 3-Dimensional object or place (for instance a shop front).

Flats are usually in the form of a tall screen of canvas stretched upon a wooden frame. Flats sometimes are flimsy and can be strengthened by a Brace which is a piece of wood used diagonally across the back of the flat as reinforcement.