Spike Drill

The initial transit along a course was always the most dangerous. The metadimensional currents were unmapped on those routes, and a navigator had to make regular course corrections in hope of finding a current that would bring them to their course before the spike drive’s protective bubble broke down in the metadimensional environment.

Once the initial journey had been made, course rutters could be shared with other ships. So long as ships regularly made the transit, any shifts in the currents could be recorded. If a route lay fallow for too long, however, the slow creep of currents would render the rutters worse than useless, and a fresh course would need to be plotted by some brave crew.

— 'Crohn's Discovery' - The Mandate Archives

The Spike Drive; an invention of Dr. Tiberius Crohn was responsible for elevating humanity form a squabbling post-nuclear war civilization to a thriving interstellar race of near-gods.
The spike drill is the main method of interstellar faster-than-light travel in the modern era.