The ability to travel faster than light was considered to be a major technological milestone in a species' development. The Federation typically subdivided civilizations and cultures on whether they had developed technology to exceed the speed of light. The species that had not yet achieved the level of technology required were placed in the pre-warp civilization category.
In 2254, the USS Enterprise encountered a faked distress call from SS Columbia created by the Talosians. The signal was keyed to register on sensors as an unknown object on a collision course which traveled with the speed of light. (TOS: "The Cage")
- See Propulsion
According to the Star Trek: The Next Generation Technical Manual and The Making of Star Trek, the speed of light is equivalent to the speed of warp 1 on the scales used by Starfleet in the 23rd and 24th centuries.
Modern physics experiments have shown that the "phase velocity" of laser light can exceed c, and some observed phenomena in quantum mechanics also exceed c. However, practical applications of these experiments do not exist because it can be shown that no information or particles can actually be transmitted faster than light by those methods. According to Albert Einstein's theory of relativity, though, faster than light travel is not possible because when an object accelerates most of its energy goes into increasing its own mass, so at speeds approaching c, all of its energy goes into this process, therefore rendering faster than light travel impossible through conventional means.