A new feature of PHost 4 is that ships (and planets) have experience. Every unit gains experience while operating on your command, and experienced units are better in various aspects than inexperienced ones.
Units have a particular amount of experience points (EP) which is normally kept secret. From that, PHost derives the unit's rank or experience level which determines the actual bonuses. You know the level of your units, so you can estimate how many points it has. PHost can be configured to support between zero and ten levels which ships can reach. It comes with sensible defaults for 4 experience levels.
In every turn, units gain new experience points. When they have accumulated a particular score, they reach the next experience level. Every unit can advance by at most one level each turn; if you have enough points to advance two levels, the excess points will be discarded.
Unlike the simple experience system in HOST, PHost's system affects the most important part of the game: combat.
Note that ship experience is not a substitute for player experience.
