A space station is a man-made structure that is designed for people to live on. A space station is distinguished from other manned spacecraft by its lack of major propulsion or landing facilities - instead, other vehicles are used as transport to and from the station. Space stations are designed for medium-term living in orbit, for periods of some months.
Past and present space stations:space habitats for large numbers of people, essentially "cities in space" where people would make their homes. Thus far all such designs are only hypothetical, and have never been seriously considered for actual implementation.