A stargate is an orbital device that allows ships to jump from one location to another in a single year, with no use of fuel and no risk of hitting minefields.
All stargates have both a mass rating and a distance rating. Ships under that mass can safely travel distances less than the limit. Over the limits, gating becomes less and less safe, as ships take increasing amounts of damage, and more and more ships simply disappear. The damage taken when gating over 5 times the mass or 5 times the distance becomes 100%; hence attempting such stunts is pointless.
The following is a list of all gates available in Stars! and their ratings.