Web is not commonly seen or used by Mortals. There has only been 1 main entity which used it as a ability; Silk: The Elemental Knight of Web. Other people that use or used web was Ywelle Tiant; a Vampire who wields Web because of her affinity to spiders.
Web is regarded amongst its patrons as the most powerful form of magic known to mortals. It been the basic structure and providence in the creation of life itself. However its extremely hard to master. Web can only be taught by those sunken to a level that only a spider can endure. Or by consistent study of Spiders.