The Terrans are humans whom have colonized worlds outside the Solar system. They are a hardy and versatile race, able to adapt to various environments. They have the innate ability to survive and flourish in even the harshest of climates.
Terran technology is very crude. They process minerals and ores to produce the materials they need to build their equipment. They rely heavily on nuclear fusion for power and use it also as an ultimate weapon of destruction.
Terrans need to build everything from scratch, as they don't have the resources to import from the Inner worlds, even Battle Cruisers take weeks to travel between the stars.
Terrans also build for all contingencies. In an emergency, many of Terran buildings can lift off and go to space. Useful for overcrowding and when under heavy attack.