- They are considered to be K-class Expedition Ships.
- Since the distance between stars is so vast, ship travel duration can extend into many decades or even centuries, so crew reproduce and create future generations of crew while the ship is in transit.
- The two terms Sleeper Ship and Generation Ship are often, incorrectly, interchanged and used to refer to either type of ship.
- Since civilizations that use such ships generally have limited means and technology for producing NAFAL starships, most are used for colonization purposes.
Library Data Referral Tree
- Colony Ship
- Habitable Zone (Goldilocks Zone)
- Planetary Engineering (Terraforming)
A ship containing a full complement of personnel intended to make a sub-light journey across space. Since such journeys take years, or even decades, the crew and passengers of the ship expect to give birth, live and die naturally during the course of the journey. The subsequent generation of the original crew and passengers being the ones who actually arrive at their destination.
Generation vs. Sleeper Ships
Generation Ships are sometimes referred to, incorrectly, as Sleeper Ships, which are similar, except that the majority or all of the passengers and crew are put into low berth hibernation for the duration of the journey. 
The original crew and passengers are usually picked for their ability to re-orient to living the rest of their lives on a ship. Re-orienting the arriving generation to life on a planet is usually more of a problem. There have been cases where the arriving generation simply refused to set foot on the planet, regarding the ship as their proper home regardless of their ancestors' desires (...when this happens, the difference between skills usable for shipboard life and skills usable for planetside life - specifically, that the arriving generation has been using the former but has had no immediate use for the latter - has often been a factor). In other cases, where acceleration to the target system took longer than a generation, a subsequent generation ceased acceleration and stopped short (in interstellar space or diverting to some other, closer system without a habitable world) in order to divert fuel for other uses. In any case, the resulting colony is often only notionally still a part of whatever culture (...let alone government or other organization) originally sent them, which may have died off back home in the mean time; FTL-enabled cultural ties such as trade and taxes are difficult to apply. 
Colony Ships establish colonies on new worlds, settlements to sustain life and provide socioeconomic commerce.
Polity Users of This Technology
The following species are known to use, have used, or posses the technology to manufacture generation ships: