Union of Galactic Interests
Interstellar travel happens with a warp drive, an engine which bends time and space around the ship, then unwraps it elsewhere in the universe. An EC-class ship can travel about half a light-year in an hour, or 12 per day. Ships have enough fuel (antimatter) to exit a planetary system and then jump to the next one to a maximum of just over 100 light-years distance. They must make their own fuel at the target system before they can jump again. This takes anywhere between a day and several weeks depending on the amount of fuel spent and the amount needed.
Because interstellar travel is so energy-intensive and requires a computationally complex pilot, most interstellar communication happens via courier.