The liner is among the most basic commercial vessels found with some ubiquity throughout known space. A liner is a passenger vessel. A liner may be a massive, mass transit solution, or it may be a smaller luxury vessel ferrying the wealthy from place to place. Because the defining characteristics of a liner are simply that it transports living things, there are many recognized forms of liner.

All that separates a liner from a shuttle is mass; liners are always starships whereas shuttles are not. Liners are thus more closely related to the Freighter. All comparison ends at the transportation of large amounts of something.