Ouch.
Damage, in general, measures how much health character can lose before dying or being rendered inoperable.
Historically, within SS13, a player’s overall damage is composed of 4 primary types: brute, burn, toxin, and oxygen.
Proposition: expanding on the damage types by adding subtypes of damage might make more sense in the context of medical experience and in other spheres:
BRUTE: Brute damage is the most common: it's caused by being hit with physical weapons, pressure, explosion blasts, surgery, and so on. Subtypes:
CRUSH: Damage for being hit with a blunt object (fists, toolbox, hammer)
SLASH: Damage of being cut with a blade (sword, saw, cleaver)
PUNCTURE: Damage if being pierced with a bullet or a stab with a blade (bullets, drill, spear)
PRESSURE: Atmospheric pressure or lack thereof (depressurization, overpressurization)
ENERGY: Previously known as a burn damage type. The second most common damage, is usually dealt by lasers, hot weapons like welding tools, electric shocks, explosion heat waves, fire and cold. Subtypes:
HEAT: Damage of being exposed to dangerously high temperatures (fire, laser burn, welding tool)
COLD: Damage of being exposed to dangerously low temperatures (being stranded in space without env suit, being stuffed in the fridge, contact with liquid nitrogen)
SHOCK: Damage of being exposed to electricity (taser, hacking failure, stun baton)
RAD: Damage of being exposed to radioactivity (uranium, refined plasma, space exposure)
CHEMICAL: Previously known as a toxin damage type. The least common (normal) damage, it's caused mainly by, obviously, toxins, acid and miscellaneous poisoning. Subtypes:
TOXIC: Damage of being exposed to viruses, poisons, bacteria or viruses, oxygen poisoning (too much O2 in the air) also counts as such (self-explanatory)
ACID: Damage of being exposed to corrosive materials (acid, being devoured by slimes)
OXYGEN: Also known as suffocation, this damage is taken when not breathing
Сlarification: doctors don’t heal the damage subtype itself, but it’s effect on different organs/parts. Any damage taken will add to its corresponding category and subtract from part's health.
Subtypes exist mainly to calculate what's going to hurt more - bones, muscles, circulatory vesicles, nerves or organs. For example, no matter if the bone is shattered by puncture or slash, the treatment should be for a physically (BRUTE) damaged bone. For more info, check out Body Systems.
Also, this way the damage from the toolbox (CRUSH) and the knife (SLASH) would be different (because it logically should be), without directly manipulating the chances of causing bleeding, concussions and other effects for every weapon and item.
Damages are shared between the different body part layers on a body part. Getting a strong hit in the head will damage mainly the head's bone structure, but also its circulatory system. If the hit is strong enough, it can even affect the brain.
Certain types of damage, like burn and brute damage, may have a direct effect on specific areas of the body; different body parts may be damaged individually. For example, if your liver dies, you may start fainting and sustain toxin damage over time.
Damages can affect many things, from your ability to talk and walk to your ability to feel pain.