Travelling in hyperspace uses fuel. If a fleet runs out of fuel while in hyperspace it will drift towards the nearest gravity well and fall back into normal space there.
Inside hyperspace, there are Deep Hyperspace zones scattered about. Fleets in deep hyperspace have half the sensor profile. Deep hyperspace generates hyperspace storms at random, which inflicts serious damage on fleets caught in it: reducing their maximum burn by 80%, adding a flat +2000 units to sensor profile, and gradually reducing combat readiness, which results in squandering copious amounts of supplies. Areas of incoming storms glow slightly, and active storms glow brightly. Extreme caution is advised when travelling through deep hyperspace; incoming and active storms are to be avoided if at all possible.
There are two types of jump points; one-way (or gravity well) points including stars and gas giants. These can only be accessed from hyperspace and can not be used in system; additionally, a star requires level 7 in the Navigation skill to be usable as a jump point. The other kind can be used to both access Hyperspace for entrance and exit. Two can usually be found in each system, an inner jump point that usually shares an orbit with the system's major planet, and a Fringe Jump Point which revolves around the Sun farther out than the farthest planet.
The Traverse Jump ability allows to fleets to exit a system from any location at a small combat readiness cost, and to enter systems via the nascent jump points at normal planets.
Only up to date for version 0.8a-RC19. It is likely still broadly correct but not verified for the most up to date data yet. Please double check the Version History