A colony ship is a popular type of landing vessel used by both corporate and military organizations. All colony ships are equipped with what is called a colony starter unit, which is a vehicle containing everything needed to jump-start a colony on a newly discovered alien world. All colony starter units come with basics like a year's worth of rations, as well as everything that should be needed to construct and maintain self-sufficiency before rations run out. Using 3D printers, a colony starter unit is able to turn raw materials into any tools programmed into its database, like a giant Autolathe.
The USDF famously uses mother ships like the Phoenix-class colony ship to carry up to ten colony starter units at once. However, it is possible to purchase individual colony starter units equipped with FTL drives. The advantage of a mother ship is the ability to launch multiple colony starter units at once without having to spend the resources for an FTL drive on each unit, nor the fuel costs of supplying those drives, plus a mother ship can provide additional supplies to the colony starter unit once it has landed. On the other hand, using individual colony starter ships equipped with FTL drives is far less cost prohibitive, allowing Trans-Stellar corporations such as NanoTrasen to make use of colony starter units when claiming new territories.
Once a colony starter unit makes landfall, it is not intended to take off again, but rather it is meant to help establish a secure footing on the new world.
Behind the scenes
Colony ships are shamelessly stolen from Halo.