The main engines used on Galaxy class spaceships, like the USS Enterprise, on Star Trek.
The warp engines use some sort of matter/antimatter reaction to propel
the ship through the galaxy at amazing speeds.
There are certain "levels" of warp. 0 being the slowest, 10 being theoretically the fastest. Nobody knows exactly what happens when the warp 10 boundary is crossed. If I recall correctly, there was a theory about inter-dimensional travel though.
Update: See below. General Wesc is obviously more of a trekkie than I am.
c (the speed of light) is 670,000,000 mph.
Old warp scale