World of the Elves, and other creatures if the Queen of the Elves allows them to exist in that world. There are several geographical locations on the Disc that are in contact with the world of the Elves, and at certain times, the worlds are closer together, the barriers constructed on the Disc side of these locations weaken, and Elves can come through to the Discworld. Likewise, people such as witches and creatures such as pictsies can find doorways to enter into the realm of the Fairies.
Fairyland is a parasitic world, a place where no sun shines and nothing grows, floating in existence searching for those weak locations where no one is paying attention and feeding off the bounty of those worlds. Once, the Nac Mac Feegle served the Queen in the theft from other worlds. Even without the pictsies in her services, the Queen's world is highly dangerous and Discworld requires protection where it is weakest.
The Dancers are huge slabs of meteorite, magnetic iron, standing in a circle, in Lancre. Since Elves detest iron and effectively weaken in the presence of iron, The Dancers stone circle is a very effective barrier against the elves. The Dancers lead into the part of Fairyland that is a world of the gray and white of permanent winter. Another known location leading to this part of Fairyland is a stone gateway on the Chalk. This gateway leads to an area populated not only by Elves but also beings abducted by the Queen such as grimhounds, Sneebs and Dromes. Other inhabitants include stinging fey (human-shaped flying creatures with dragonfly wings that bite viciously), Jenny Green-Teeth, and headless horsemen. Also in a permanent snowy winter, there is an added unfinished quality to the landscape. It is as though details such as leaves and bark on trees don't exist until closely observed. Due to the dromes and the Queen's power to control dreams and make them solid, reality is not to be trusted in fairyland; words, dreams, and even thoughts have power. Time moves much slower in comparison to Discworld, and the Queen's prisoners from other worlds will never grow old.
A very different place, also belonging to Elves is a hot, steamy world ruled by the King of the Elves; this world is in contact with the Discworld at The Long Man, a location in Lancre consisting of three burial mounds in a suggestive arrangement. The Long Man also leads into the labyrinthine Lancre Caves.
Once, when both the Elf King and the Elf Queen ruled together, Fairyland was a different place. It is said that the Queen was always happy then and wasn't so cold. There were flowers, birds, and summertime. This version of fairyland was destroyed by an argument of magical words between the King and Queen. The King then left the Queen's fairyland for his own world. (The Wee Free Men, Chapter 9)