There are a large number of different types of cultures and civilisations in a galaxy. WorldGen defines these as civilisations, and this determines how cultures are generated and built, and the sort of worlds they can be found on.
It is up to a planet type to define which civilisation type to use when populating the world. The civilisation type though is not recorded against the planet after creation - instead it determines what facilities are created.
A Facility is some aspect of a civilisation that produces and consumes goods, so facilities are central to the economics of worlds. A civilisation type defines what facilities are on a world, and these are what are actually recorded. The broad types of facilities are:
The most well known of groups living in asteroid belts. Live by mining resources from asteroids and selling them on to traders. Belters tend to be very independent, but tend to have good contacts with the outside world, since they need that for trade.
Dwell in dust rings around stars, living off the material that can be collected from the rings. Because of the low density, it's not very productive, but they can get by.
Hermits are small groups of people that try to live apart from the rest of galactic society. They often hide in hollowed out asteroids, and are known as Rock Hermits. They will have an H spaceport at best.
Planetary civilisations are gravity-bound. The most sought after are those on Type I planets, which are Earth-like and everyone can live outdoors. Type II planets are harder to setup a colony on, because they are hard to grow crops on, but people can still mostly live outdoors.
There are various types of civilisations, some of which are described below.