whats the myth behind vampires?

Vampirism is the practice of drinking blood from a person/animal. In folklore and popular culture, the term generally refers to a belief that one can gain supernatural powers by drinking human blood. The historical practice of vampirism can generally be considered a more specific and less commonly occurring form of cannibalism. The consumption of another's blood (and/or flesh) has been used as a tactic of psychological warfare intended to terrorize the enemy, and it can be used to reflect various spiritual beliefs.