A fairy (also fay, fey, fae, faerie; collectively, wee folk, good folk, people of peace, fair folk, and other euphemisms)Briggs, Katharine Mary (1976) An Encyclopedia of Fairies. New York, Pantheon Books. "Euphemistic names for fairies" p. 127 ISBN 0-394-73467-X is a type of mythological being or legendary creature, a form of spirit, often described as metaphysical, supernatural or preternatural.

The word "fairy" derives from the fae of medieval Western European (Old French) folklore and romance, one famous example being Morgan le Fay. "Fae-ery" was therefore everything that appertains to the "fae", and so the land of "faes", all the "faes". Finally the word replaced its original and one could speak of "a faery or fairy", though the word "fey" is still used as an adjective.

Fairies resemble various beings of other mythologies, though even folklore that uses the term "fairy" offers many definitions. Sometimes the term describes any magical creature, including goblins or gnomes: at other times, the term only describes a specific type of more ethereal creature.Briggs (1976) p. xi

Characteristics

Fairies are generally described as human in appearance and having magical powers. Their origins are less clear in the folklore, being variously dead, or some form of angel, or a species completely independent of humans or angels.Lewis, C. S. (1994 (reprint)) The Discarded Image: An Introduction to Medieval and Renaissance Literature. Cambridge, Cambridge University Press. p. 122 ISBN 0-521-47735-2 Folklorists have suggested that their actual origin lies in a conquered race living in hiding,Silver, Carole B. (1999) Strange and Secret Peoples: Fairies and Victorian Consciousness. Oxford University Press. p.47 ISBN 0-19-512199-6 or in religious beliefs that lost currency with the advent of Christianity.Yeats, W. B. (1988) "Fairy and Folk Tales of the Irish Peasantry", in A Treasury of Irish Myth, Legend, and Folklore. Gramercy. p.1 ISBN 0-517-489904-X These explanations are not always mutually incompatible, and they may be traceable to multiple sources.

Much of the folklore about fairies revolves about protection from their malice, by such means as cold iron (fairies don't like iron and will not go near it) or charms of rowan and herbs, or avoiding offense by shunning locations known to be theirs. In particular, folklore describes how to prevent the fairies from stealing babies and substituting changelings, and abducting older people as well. Many folktales are told of fairies, and they appear as characters in stories from medieval tales of chivalry, to Victorian fairy tales, and up to the present day in modern literature. Some tales tell of fairies having the ability to turn invisible. Once invisible, fairies are said to steal single socks from laundry baskets.