The method of supra-light travel used by all intelligent species is usually called, by the Jao, the "Frame Network." The method involves warping spacetime using extremely powerful generators positioned in at least three widely spaced locations in the stellar neighborhood. (Three will work, but is risky; four is better; five is ideal; more than five is redundant.) These "framepoints" must be at least three light-years apart, but are not effective if the distance between any two extends much more than eleven light-years.
Existing framepoints allow ships to cross the stellar distances between them in what is effectively an instantaneous transition. There is theoretical debate over whether the transition is "really" instantaneous. But from the subjective standpoint of any human or other intelligent species, the travel is instantaneous. The dispute is whether or not it actually requires a few nanoseconds.
In essence, two framepoints working together are creating what can be called an artificial wormhole. New territory, where there does not exist a framepoint, can be reached in one of two ways. One way is to use sub-light exploratory ships. Once arrived at a suitable location for a new framepoint, the ship (or multiship expedition) can begin to create the new framepoint, which can then begin to participate in extending the entire Frame Network.
Of course, this method of extending the Frame is very slow. The other method is to use existing FP generators to create what is called a "Point Locus."
Triangulating (more often: quadri-angulating or quint-angulating) their power, these framepoint generators can create a temporary Point Locus at a distance. For a certain period of time, ships can travel to the Point Locus from any one of the FP generators which created it.
This is the normal method used for invasion fleets, since it is impossible to invade a framepoint held by an enemy. (They just "turn off" their end of the Network and the invaders vanish, no one knows exactly where.) Invaders from the outside can triangulate on an enemy solar system, create a point locus which is independent of the enemy's side of the Network, and send an invasion fleet that way.
The expense and risk involved are considerable, however. Point loci tend to be unstable over any extended period of time, so the window of opportunity for an invasion is limited. To use an historical analogy, each invasion is like a major amphibious assault during World War II. If a large enough beachhead is not secured quickly, the invasion will face disaster by being stranded and overrun. Moreover, because of the impossibility of matching loci in open space, the point locus must always be created within the photosphere of a star. In essence, the star itself serves the participating frame generators as a common target. But that obviously presents its own set of dangers.
How unstable and temporary a point locus proves to be varies according to a wide range of factors. These include: the number of FP generators used, distance, and a multitude of more subtle factors involving a lot of specific features of the galactic neighborhood—dust cloud densities, nearby novas or neutron stars, etc. Creating a point locus is as much an art as a science, as well as being extremely expensive, and is never something to be undertaken lightly.