A vampire is a human being who has died and been resurrected by certain supernatural means and endowed with certain supernatural abilities and limitations, most notably a need to drink blood in order to sustain his or her existence. Vampires are also called the "undead," inasmuch as, even when active, they are not truly alive in the same sense that ordinary human beings are; indeed, they can be described as being technically dead. Most vampires possessed superhuman strength anywhere from ten to twenty times as great as the strength they had in mortal life.