Well this post is going to be what it says on the tin. An attempt to answer the question. Do keep in mind that this is merely my take on this because it really does depend on who you ask.
Generally speaking a Vampire is someone who requires some source of external (life-) energy for one reason or another. Answers to why range from basically describing it as an unrecognised medical condition to stuff about reincarnation and souls to the explainations that I personally subscribe to which is simply that some of us don't properly produce, keep or access our energy through no fault of our own, creating the need for some sort of extra source of energy. Most vampires can agree that that energy has to come from people, that it has to be life force. Now there are multiple ways of feeding and preferences range and not everyone benefits from everything equally. There are energy vampires like yours truly, who feed of the energy of other people, that ranges from energy from a single person (donor) to the ambient energy of a crowd, but there are actually some vampires who drink human or animal blood, usually in small quantities. We call those 'sanguinarians' and while I very much do welcome Sangs here, I will not that I have absolutely no experience with that stuff and probably won't talk a lot about it.
So to summarise, a vampire is simply a person who requires extra energy. Well the real ones anyway but the real vampire community is vast and does also include a third category of people next to sangs and psis (energy vampires) and that's lifestylers. Lifestylers are basically people who embrace the aesthetics and general vibe without having this extra energy need. Lifestylers may stay out of the sunlight, dress goth, wear fangs, they may even drink blood, but they don't have a need for the energy. And as far as I'm concerned? That's fine. Whatever floats your stoat, my friends, if it's fun, do it, if you identify as otherkin or something along those lines and it makes you happy, do it, if you wanna do it for any other reason, do it. Just be aware that not every 'vampire' you come across has the need for energy. There are lifestylers that don't need the extra energy, there are vampires that look like soccer moms.
And with that clear, some more clarifications about vampires. Some things that are purely fiction include but are not limited to: Burning in sunlight, being repelled by garlic, religious symbology etc. mind controlling people (though some of us are into hypnosis (which is not mind control)), not being able to eat real food, being immortal, superpowers of any sorts beyond what is possible through energy manipulation in the magickal sense and, last but not least, no. We can't turn you into a vampire. You probably don't want to be one to begin with. Go dress goth and wear fangs, become a lifestyler. You don't want to feel tired and drained whenever you can't take energy from someone else.