A space habitat, space settlement^[1] or spacestead is a theoretical space station that rotates to simulate gravity and is set up to be like an environment on Earth, with landscaping, one or more settlements where people live, etc. Space habitats would be very big, from 500 meters in diameter,^[2] to several kilometers in size.^[3]

Proposed designs include but are not limited to:

• O'Neill cylinders - Cylinder shaped spacesteads with habitable space all over the inside surface with the exception of the ends. Two joined cylinders form the space settlement. ^[3]

• Stanford toruses - Donut shaped habitats in which the land, settlement, water, etc is on the outer part of the interior surface, leaving the other half to be the sky. These would also have spokes and a central hub in the middle.

• Bernal Spheres - Spherical habitats from 500 meters to more than one kilometer in diameter,^[2] with part of the inner surface being habitable land.

• Bishop rings - Essentially smaller Stanford toruses without central spokes.

• Birch Worlds - Spherical habitats one or two light-years in diameter built around a galaxy's supermassive black hole.

Space habitat can also mean a base or enclosed settlement on or beneath the surface of a planet or large natural satellite or floating in its atmosphere.