A true "werewolf", according to most legends, is a human being that uncontrollably transforms into a wolf during a full moon. The original werewolf curse transformed a Shapeshifter Wolf into a Werewolf, effectively taking away the ability to control the shift but also taking away the ability to think as a human while in wolf form. Werewolves, when in wolf form, have uncontrollable rage and hunger. They are driven to kill everyone and everything they encounter, regardless of their relationship as humans. The curse causes these wolves to lose all control of their minds, and when they wake up in human form in the morning, they don't remember anything (though they may revisit certain memories in dreams). It is this form of werewolf that can transfer their condition through a bite, assuming of course that the human being bitten survives the attack.
The rest of this site describes werewolves in these terms.