A civilization in Starspan is, well, a civilization ... basically, a population on one or more worlds unified (tightly or loosely) under one flag. A civilization may have one or more internal factions vying for power. If a faction meets certain requirements, it splinters off its mother civilization to become one of its own. At the beginning of the game, some Civilizations may start with rival civilizations. For instance, playing a human empire, there may be an American civilization, a United Nations civilization, and a Liberated Mars civilization. They may even have split ownership of worlds; Earth may be 60% controlled by the United Earth civilization and 40% controlled by the American civilization. They can coexist peacefully on the world, or one could battle the other(s) to control over more (or all) of the world.