If a ship ends the fight with 100% damage or more, it is destroyed, and the opponent is declared winner of the fight.
This also applies to Lizard ships: although they can fight until they reach 150% damage, they cannot survive any further with more than 100% damage.
If a ship ends the fight without crew, the enemy can capture it. He will man the ship with an emergency crew of up to 10 crewmen (for simplicity, the capturing unit doesn't lose crew by doing that). The ship will become passive for further fights this turn.
Unlike in HOST, planets can capture ships in PHost.
If a ship has lost shields, crew or ammunition, or got damaged in fight, it will carry over this damage to further fights this turn. Shields will be recharged for the next turn, but damage remains until you repair it. The first chance for repair is given after combat: ships can repair themselves using supplies (see Supply Repair).
If a planet ends the fight with 100% damage or more, it is captured. The fight will have destroyed all its offensive potential, so all the defense posts and the starbase will be destroyed. At the default configuration, all colonists will have been killed (see ColonistCombatSurvivalRate), and the planet will be manned with a single colonist.
Damage is handled a little different for planets compared to ships: whereas a 30% damaged Annihilation Class Cube with Mark 8 Tubes is still an Annihilation Class Cube with Mark 8 Tubes, the planet (and its starbase) will lose some of the defense posts making up its strength: if a planet with 50 defense posts gets 30% damaged, it will lose 30% of its defense, and begin the next turn with 35 defense posts. It will therefore start the next turn as an undamaged planet that happens to be weaker than the turn before. Put in other words: whereas ships keep their strength but accumulate damage, planets simply lose strength, but don't get permanent damage.
If a planet/base combo fires ammunition, it will first take the ammunition from starbase storage. The base will also receive damage and lose tech levels if too badly damaged.
See also: Combat results for ships, Combat results for planets.