According to Jim, vampires do not exist in the world of Skin Deep.
[However, that does not mean we can't define them just a bit for you anyhow ;P]
Vampires are one of those creatures of the night who have been around as long as many of the other things which go bump in the night. They've been around (documented by mortals at any rate) since around 6,000 or so years ago - give or take a few centuries maybe.
While there is such a backlog of differing info about vampires, what creates them, what repels them, and other general rules and such about them, here are some of the more common or 'public knowledge' as it were, of the vampire class:
Repelled by - garlic, crosses, fire, sun light, moving water such as rivers or creeks, wooden stakes, holy water
Born from - Being bitten by a vampire (most popular way to be 'turned' in many folklore, but funny enough if you do a bit of digging you'll see that there is really a good handful of other ways one can get those pointy canines and veritable diet of warm blood every night) some tales requiring that the blood be completely or at least almost so drained from the body before turning can ensue.
~ as a side note to this, many legends also put in that there is a head vampire which when going around biting new victims, these fresh bloods become the underlings and have to obey whatever is told of them through the link of blood which connects them through their 'master'. It is difficult to disobey, and if one were to get to doing such things, it is even more so to keep their 'dracula' from finding out of their betrayal.
The one biggest 'rule' of vampires, (not including any of the fore mentioned) that I can think of is that they HAVE to be invited into someones house to be able to cross the threshold, otherwise they can't step a foot in. Sometimes it can even be revoked. Though the technicality of it being it would have to be private property, such as someones home - not a public park, or library where in such a case, everyone is invited, so if you're avoiding a vampire, try not to go to public areas at night, eh?
References (apart from common knowledge of folklore, that is . . .)