Interstellar Travel Basics
The galaxy is massive, and travel between systems would be impossible if not for a number of Arcane and Technological advancements.
Propulsion Systems
"Traditional" Propulsion
Prior to the advent of the Jump Drive, space travel required vast quantities of fuel to generate the required amounts of thrust. This created a problem, in order to gain more thrust you needed to add more fuel, but more fuel added more mass, thus reducing thrust. The Lyrium Drive, a self-contained alchemical reaction, could generate nearly limitless thrust without the need for enormous stores of fuel, which drastically reduced the mass of ships. Lyrium drives are standard on all interstellar vessels and are often simply referred to as the ship's "engines".
Point-to-Point Gate Travel
Originally developed my Dwarven Engineers, this system consists of a serious of orbital 'gates' that once connected, create near instantaneous travel between two points over vast distances. Originally developed by the dwarves to service their mining operations, these P2P Gates have since been adapted for everything from cargo transport to moving people around the galaxy.
Jump Drive
The Advent of the Jump Drive opened up the Galaxy. The jump drive taps into the Plane of Positive Energy, allowing a ship to pass into that plane and travel immense distances. Crossing a sector (one square on the Galaxy Map), a feat that once took years now only takes hours, allowing travel across the galaxy in mere days.
System Communication
Communication across long distances of space has always been a problem, creating massive delays between the sending and receiving of a message that could easily span hundreds of years.
Luckily, with the advent of the Jump Drive and the use of The Plane of Positive Energy a network of transceivers have been littered throughout the galaxy that provide free and galaxy wide communication and sharing of information. This system is known as the Cortex and acts a lot like todays World Wide Web.
Note from the Game Master: I don't want the ins and outs of intergalactic travel to be a major focus of the game so, much like Star Wars, I'm going to simply hand wave the majority of details.