Habitat

Definition

A habitat is an environment in which an organism, or group of organisms live in symbiosis.

Mars habitats

The environmental conditions on Mars are hostile for humans without life support systems; examples of the factors which make the surface of Mars uninhabitable include the thin, oxygen-poor atmosphere, the lack of easily available liquid water and the extremely cold climate. The habitat of any human visitor to Mars would have to be set of self-contained artificial environments such as buildings, rovers and space suits.

Terraforming has be suggested as a way of making the whole surface of Mars habitable.