Huldufólk or hidden people are elves in Icelandic and Faroese folklore. They are supernatural beings that live in nature. They look and behave similarly to humans, but live in a parallel world. They can make themselves visible at will. In Faroese folk tales, hidden people are said to be "large in build, their clothes are all grey, and their hair black. Their dwellings are in mounds, and they are also called Elves." Some Icelandic folk tales caution against throwing stones, as it may hit the hidden people.