Fire damage is done by the Solar Scorcher, Flamer, Incinerator, Grenade (Fire), Molotov Cocktail, Fire Geckos and Shotguns loaded with Gecko's Breath ammunition.
The Fire damage resistance is a combat statistic. Any fire damage done to a player or critter is first reduced by a percentage (fire Damage Resistance) and by a set amount (fire Damage Threshold).
Every armor has a DR and DT for each damage type and it is mostly through armors that a player can increase his DR and DT statistics.
Other damage types: