A warp reactor (also known the warp core) is the main energy reactor powering the propulsion system on warp-capable starships. It is a large engine that runs on antimatter instead of using electricity or chemical fuel. When matter and antimatter collide it creates a tremendous amount of energy. That energy is channeled through magnetic plasma conduits that lead to two large cylinders on the outside of the ship called warp nacelles. The nacelles contain warp coils that create the subspace displacement field.
The subspace displacement field changes the geometry of space surrounding the warp nacelles. In the process, a multilayered wave of warped space is created, and the starship cruises off to its next destination at hundreds of times the speed of light relative to normal space. Within the warp field, however, the starship does not exceed the local speed of light and, therefore, does not violate the principal tenet of special relativity.