In architecture, a deck is a flat surface capable of supporting the weight, similar to a floor, but typically constructed outdoors, often elevated from the ground, and usually connected to a building. The deck of a house is generally a wooden platform built above the ground and connected to the main building. It is generally enclosed by a railing for safety. Access may be from the house through doors and from the ground via a stairway. Residential decks can be constructed over steep areas or rough ground that is otherwise unusable. Decks can also be covered by a canopy or pergola to control sunlight.