|This article is about an older version of DF.|
Remains are what are left over after vermin are killed.
All corpses will rot away, eventually. All corpses will leave behind their possessions where they died. Corpses left to rot in an enclosed space, such as your fortress, will emit miasma. After a time, the flesh will rot away, leaving behind bones and a skull.
If the corpse was involved in a fight before death, it is possible for parts of the corpse to be scattered around. Hammerlords and the like are notorious for blasting apart bodies in one swing. Should a corpse be severed from its parts, all the equipment you'd expect to be on the limbs will usually be located where the limb fell.
The corpse of an animal can be valuable to your dwarves. When brought to the butcher's shop, a butcher will dice up the corpse into meat, bones and fat. Depending on the animal, raw hide and skulls may also be rendered. Dumping the corpse in a refuse pile near the butcher's shop before it rots will also trigger the butcher task. A hunter who survives long enough to return his kill will bring it directly to the butcher's shop. Corpses of animals are hauled using the refuse hauling labor.
The corpse of a dead dwarf (and favored pets) should be buried. To avoid unhappy thoughts, the sooner it is placed in a burial receptacle, the better - this requires the burial labor. Any dwarf that dies will make unhappy thoughts for anyone it is related to, but left to rot where it is, all dwarves passing by will have unhappy thoughts. Further, any friends of the dwarf will become increasingly upset at the lack of care and attention being given to the would-be honored dead, with a further unhappy thought when the corpse begins to emit miasma, and another when it rots away to a skeleton.
Invader corpses will lie in a heap with their clothing, armor and weapons, if any. Everything but the corpse is forbidden by default if lost in combat; but your dwarves will still retrieve the corpses and/or bodyparts and dump them in your refuse pile. This can be a very bad thing during a siege, as dwarves that are not locked away and do not have hauling jobs turned off will walk into the middle of a battlefield to retrieve them. So you may wish to manually forbid the corpse or keep your dwarves inside.