Fairies are the most varied of species. They're slightly smaller than humans, averaging at about five feet (the tallest are 5'4 and the shortest are 4'6) when fully grown. They have wings that they can make appear or disappear, which vary in appearance. They have eyes just like a cat's, with the extended iris and everything, the color filling the entire eye. They live to be about three hundred years old in general, and their magic is what varies most of all.
There is not much, aside from their eyes and wings, that proves them to be a fairy, except for birthmarks on their ankles which look more like tattoos: vines, flowers, some sort of design that is generally nature-based, usually based on their magic. Their magic can be nature-based, based on spoken word, or even spiritual and inter-dimensional, but the last kind is very rare. They also have their one element, as all mages do, but there is another perk for them: some have one element and another type of magic, but others can control all four elements... only the four elements.