Space station (Earth-5875)

A space station is a platform or facility built for multiple roles, including habitation, defense, and research, either in geosynchronous orbit of a planet or in deep space.

Human
The first human space stations were constructed across the Sol system during the breakthrough of space exploration in the 21st century and later started to be employed en masse for the next centuries in the intrasolar and extrasolar colonization. By the 26th century, space stations under the UNSC and the UEG came to fill numerous roles, including the construction and docking of starships, colonial habitats, defensive outposts, and scientific facilities.

Covenant
The Covenant employed many space stations, most notably High Charity, their capital city, which housed billions of inhabitants and constantly moved between systems in the Orion Arm of the Milky Way galaxy.

Forerunner
Forerunner "space stations" are more unconventional when compared to those of humanity and the Covenant, as most of them are what is best described as mobile megastructures, such as the Halo Array, the Ark, the shield worlds, the Citadel and the mass relays.

Trivia

 * Space station on Wikipedia.