Stereotypically, a 'fairy' is a generic "little
pixie with
wings"
Tinkerbelle sort of creature. However, "fairy" is actually a very
general term covering almost all
humanoid earth spirits.
Brownies,
pixies,
pysks,
dryads,
gnomes,
leprechauns are friendly
fairies. Any fairly
small and/or
ethereal otherworld being with a generally
humanoid form can be considered a fairy. Some
fairies, however, are
malign and should not be dealt with]
Fairies usually have some "magical" abilities, although some more than others. Brownies move quietly and can disappear even as you watch them (and they're reputed to bless houses, and be exceptional leather-workers.) the winged fairies/sprites may have elemental powers, of course the magic of flight, they can create fairie rings to hold ritual and celebration in, and they can be asked to join in a human circle for magical aid.
Fairies are very shy and hard to find. Most are afraid of humans finding them, although they love to watch people. They can be attracted, however, by convincing them you are harmless and will treat them kindly. Fairies may be attracted to your dwelling by notice of magical work going on. But they can be attracted, and convinced to *stay* by leaving them gifts. Set up a small shrine to them. leave them shiny things (foil is wonderful) and blue thread. leave flowers or living plants they can play and hide in, and leave them food. Honey, fruit (especially strawberries), and bread will attract them. For drink, clean cold water, red wine, or their favorite, cold rich milk. it may take some time for them to notice, and to decide to stay, but if you can attract any form of benign fairy, it is for the best. They will frequently bless your dwelling, help keep malign energies out, and generally be friendly to the environment. (However, they can be mischievous as well--but it's all in fun. if they are willing to tease you, they're willing to trust you enough to let you know they're there.)