Undead is a condition wherein a person's body ceases to go on living, but the person is too stupid to know the difference. In most cases, the undead refers to vampires, but may also refer to zombies, mummies or reanimates. In the case of vampires, a human being has their blood drained by a vampire, at which point they either die on their own, or die after then consuming the blood of a vampire. In either case, the person then rises from the grave as one of the undead. They have a mind and their bodies continue to function, but this is perpetuated through supernatural means as their normal life functions have ceased to exist. They do not have brain waves, beating hearts or a serviceable respiratory system. They also don't poop.