All space ships are equipped with a warp drive device. The warp drive creates depleted vacuum by repeatedly 'compressing' vacuum between two polar discs, draining all energy neutrons and quarks out of it. A laser-locked field is then created to hold the ever-increasing depleted vacuum bubble until it has enveloped the whole ship. When that happens the ship is able to enter FTL speed.
Although initial experiments with the warp drive were very encouraging technology wise, problems arose in regard to navigation. Once the ship has attained FTL speed, it is very difficult for it to act or react to the world, such as for communication or scanning purposes. Numerous experiments were made, for example with compactified dimensions radio, but without success. The unpredictable nature of quantum mechanics made it very difficult to create a stable enough vacuum bubbles to allow for precise time measurements due to fluctuating speeds.
Finally, a solution was found. It was discovered that gravity capacitors similar to the control system used in stargates were able to pick up gravity signals from 'normal' space while the ship was on FTL speed. By locking the capacitor onto one of these signals, the ship travels to it. The bubble is then automatically dispersed once certain distance from the gravity well is acquired. The only problem is that these capacitors can only efficiently pick up signals from gravity wells of certain size or above, with the minimum being a small moon or a cluster of asteroids. Also, in order for the gravity capacitor to align correctly on the destination object in relevance to the position of the sun, it must follow a relatively narrow route towards it, resulting in a fairly restricted emerge area for the ship.
This puts some limits on the warp drive's usage, but as all major objects in a system can be detected, this is not such a great problem. Furthermore, it is now possible to construct 'fake' gravity wells on space stations and stargates, which can be detected and thus homed onto by the gravity capacitor that is part of a ship's warp drive.