Jumpspace
The basic concept of interstellar travel: that of an alternate space. Theoretically, jumpspaces are alternate spaces, each only dimly understood from the standpoint of our own universe. Jump is defined as the movement of matter from one point in space (called normal space) to another point in normal space by travelling through an alternate space (called jumpspace). The benefit of jump is that the time required is relatively invariant - about one week. If the distance travelled is greater than can be covered in one week in normal space, then a gain has been made. Jumpspace makes possible enormous gains.
Entering jump is possible anywhere, but perturbations due to gravity make it safest to begin a jump at least 100 diameters out from a large massive body such as a world or star. Ships are naturally precipitated out of jumpspace before they get too deep into a gravity field.
Normal jumps take 168 hours (plus or minus 10 percent) to complete, regardless of the distance travelled. Sometimes a jump goes wrong. Catastrophic failures (called misjumps) can destroy the ship and its crew. Other failures can destroy a drive or send a ship in the wrong direction. Some misjumps reduce a jump-6 to a mere jump-1, or convert a jump-1 into jump-10, 20, or higher.