Warp factor (symbolic abbreviation wf), alternatively known as time warp factor, is a unit of speed. Another common abbreviation is "warp". The value is given after the unit (Warp Factor 5, or Warp 5). The increase in warp factor speed values corresponds to a non-linear increase in actual velocity. The most common usage is to describe the speed of a spacecraft traveling at a faster than light speed, using a warp drive. Sublight speeds can also be measured in warp factor values, such as "warp .5". Since warp drive was first used by Zephram Cochrane in 2063, two methods of scaling warp speeds have been used.
Although the TNG Scale has proved highly successful in use, recent advances in warp drive have brought its practicality into some question. In 2312 it seemed unlikely that Starships would get beyond Warp 9.9 for a very long time, but modern vessels are capable of Warp 9.97+5 speeds and some predict that the next twenty years will see ships which can travel in the Warp 9.999+ region. While there remains no engineering difficulties with these numbers, it is becoming problematic for bridge crews to keep track of a tactical situation while having to use numbers to three significant figures. Although nothing definite has yet emerged, several proposals for new warp scales are currently under consideration by Star Fleet.