Basic Appearance:
The vampires in Twilight are all extremely beautiful. This is because if the vampire was good looking or beautiful in their human life they will be more so as a vampire. Whereas is they were not so good looking as a human they are a normal or slightly beautiful vampire depending on their human appearance.
Skin:
Their skin is very white like in most vampire legends as well as icy and hard to the touch. The major difference between most legends and the Twilight vampires is that they
can go in the sun except they sparkle and the sparkling would give them away.
Eyes:
Most vampires have red or burgundy eyes that slowly turn black as they become more hungry. But the Cullen’s (and a very select few others) have golden eyes because they have given up human blood. This is why they call them selves vegetarians.
Speed:
Vampires gain speed when changed. They are all incredibly fast but Edward is one of the fastest. So much so that you actually can’t see him when he runs as fast as he can. Other vampires are just blurs when they run. Not only do they acquire physical speed but the ability to talk faster as well, to fast for the human ear to comprehend.
Strength:
A new vampire is extremely strong, when they are less than a year old they are the strongest they will ever be. Emmett is the strongest of the Cullen’s. They have to make sure to control their strength carefully. Edward has to be so careful around Bella that he can never let his guard down not only out of fear he might drink her blood but because if he’s not careful he can accidentally crush her. Their diet can have an effect on strength though not much of one. Human blood gives the most followed by large game and the least would be small game.
Weapons:
To Quote Edward from Twilight:
"As predators, we have a glut of weapons in our physical arsenal… much, much more than really necessary. The strength, the speed, the acute senses, not to mention those of us like Edward, Jasper and I who have extra senses as well. And then, like a carnivorous flower, we are physically attractive to our prey…We’re also venomous."(TW20)
They have very sensitive hearing, smell and sight. The Venom is in their body like blood and coats razor sharp teeth (that are not fanged). It is also what causes the change from human to vampire. The Venom doesn’t harm the skin but once it reaches the bloodstream it begins to either kill or change the victim. (this will be explained more in a different section)
Physiology:
Some of the changed that vampires go through are “their physical appearance is enhanced, their eye color changes, their hearing and eyesight becomes more acute, their heart ceases to beat, they no longer need to breathe.” (lexicon, physiology) The body is frozen as it is the moment they are changed (so their hair and nails will never grow ect). Their saliva is replaced by the venom which helps the digest human food when they must (to fit in usually) but they must get rid of it as it is very uncomfortable. They can no longer sleep and they have no human fluid left in their body. If you are able to cut a vampire (unlikely since it would be like cutting marble) they would only bleed if they’d just drank a lot of blood, otherwise it would be venom.
Blood:
The longer a vampire goes between feeing the weaker they get mentally. They start thinking less rationally and more animal like. Animal blood does not appeal to vampires at all but they can drink it for energy instead of human blood. The bigger the animal the better it tastes. Rarely will a vampire come across someone whose blood ‘sings’ to them this has happened twice to Emmett and now to Edward. Emmett unlike Edward couldn’t control himself and took the blood both times. Edward fights the urge because of his love for Bella and mental strength. Some vampires (like Jasper) can tell no difference in the ‘flavor’ of human blood and some even more rare than a human who’s blood ‘sing’s are the vampires like Carlisle that can easily resist human blood. It’s nearly impossible to stop drinking after you have stopped which is why so few vampires are created. This is how Edward knows he truly loves Bella because he was able to stop himself from draining her when he had to get the venom out of her blood after James attacked her.
Becoming a Vampire:
It is a very painful processes. It feels like the person’s blood is on fire. If the vampire doesn’t drain the human completely of blood and the venom is allowed to spread for a few days the human will become a vampire. The time it takes depends on how close to the heart the bites are and how much venom is in the bloodstream. Once again quoting Twilight "The greatest pain begins when the venom is all the way through the body, through the heart, and it starts meeting itself in the veins again and then burning them dry. It moves slower than blood because it’s thicker. Each beat of the heart can only push it so far. The changing/burning process is slow. The venom has to leak through to every cell before it ends." The process is over when the heart stops.
For additional information visit the Twilight Lexicon. All the information above was gathered with help from the lexicon.
Twilight Lexicon - Vampires 
About Vampires
