Faery or fairyland is the world in which fairies reside. Some say
that the word "faery" means magic, but that is because, to most
mortal eyes, the world seems unreal and lawless. By fairy standards the
land of faery and its ways are natural and orderly. "Faery" is
merely a descriptive term with which mortals acknowledge the living land
and extension of immortal beings called fairies.
Fairies exists all over the world. In Persia they are called Peri,
in Greece Fata or Destinies. In Provencal they are Fada, in Spanish Hada.
The names all imply fate. In Ireland they are the sídhe (pronounced
shee), a name they have retained from the ancient days when they were recognized
as gods. In a group they are the daione sídhe or fairy people;
singly each one is siog (sheogue). Some say they get their name
Aes Sídhe (folk of the sídhe hillock or mound)
from the large sídh or mound in which they inhabit; but others
claim that the hillocks got their name from the fairies' habitation of
them. The point is still disputed.
Most often the Irish Fairies are called the good people or the gentry.
In Greece mortals called the blood-thirsting Furies the Eumenides or the
kindly ones in the hope that they would not destroy their lands or people.
In Ireland the title "the good people" serves the same function,
because the fairies, quick to be offended, must be placated or they might,
in a moment of anger, devastate the crops or cause mortal children to sicken
and die. What is good for a fairy may be fatal for a mortal; so we hope
by flattering them, they might keep us favourably in mind.
Source: Carolyn White "A History of Irish Fairies"