Hyperspace (called darkspace by the Yuuzhan Vong) was the alternate state of existence used by starships to achieve faster-than-light travel. It was a phenomenon not completely understood by scientists; it was alternately described as a parallel universe, an extra dimension of space, an alternate mode of physical existence, or simply the universe as viewed traveling faster than the speed of light.
Normally, baryonic matter obeys physical principles of relativity: they increase asymptotically in mass as they approach the speed of light, requiring more and more energy to approach it, and thus always remain below this threshold. Tachyonic matter, on the other hand, existed solely above the speed of light, and could not pass below said threshold. Hyperdrive technology allowed sentients to break this barrier and allowed slower-than-light starships to leap past the barrier and reach speeds many thousands or millions of times that of light.
This principle was first discovered by the ancient Rakata.1 The Rakatan Force-enabled drives allowed them to create a galaxy-spanning empire. Some of the earliest hyperspace-utilizing artifacts (such as strange arches and matter transmitters found on ruined worlds, or the Gree hypergates), cannot be replicated by modern hyperdrive technology.[source?] Corellians and Duros were the earliest able to create technological versions of the Force-enhanced Rakatan devices through reverse engineering, allowing them to build the first true hyperdrives. Consequently, despite common usage, relatively little is known about the true nature of hyperspace. Popular theories say that hyperspace utilizes another dimension to “sidestep”, as it were, the light “speed limit”. Others theorize that it phases matter directly into another universe, similar to otherspace or subspace, and thus gain superlight speeds. Whatever the case, many complex scientific principles were known to modern hyperdrive engineers which allowed for myriad different uses of this faster-than-light phenomenon.
For the first 21,000 years or so of the Galactic Republic, hyperspace coordinates were plotted with the aid of hyperspace beacons, space stations placed in open space, distant from gravity wells, where ships would download data provided by the Republic Spacelane Bureau. Around the time of the Mandalorian Wars, navicomps replaced the beacons, making hyperspace navigation much more autonomous.