Deep Space 9, a Cardassian space station
A space station is an artificial structure in space, often built to support life. Space stations can serve many purposes, including research, defense and starship maintenance. Space stations can be in orbit of a planet, or be completely free floating in space.
Space stations are used by the Federation, the Cardassians and other races. They can be used as outposts often located in 'frontier' areas or along interstellar borders; research stations specialized in scientific research; shipyards specialized in the construction of starships, or as an orbital component of a Starbase such as a spacedock.
Stations that are positioned on the edge of the Federation border or, in the case of Deep Space 9, in neutral territory close to the Federation border are labeled as Deep Space stations.