To my knowledge they are apparently little tricksters who lived in the forrest and would reak havock on nearby villages if they go too close to the woods. Then again there are other myths that say they were our size and were beautiful but would "trick" us to the point of rape so... Depends on who you ask but, if they were real they either aren'there anymore or they're really good at hiding.
Well it's hard to teach you everything in a single forum post, it's kind of like asking for us to teach you everything you learned in high school in a forum.
Fae are like spirits of nature and they aren't the sunshine sweethearts from stories. They are, however, like Tinkerbell, can be nice, but very spiteful if upset. They like sweets and favour saffron, they also hate greed. If you are working with faeries always leave a little extra for them. [Example if you have a fruit tree, leave some fruit for them, if you're drinking tea, make a cup for them. Be sure it's extra sweet.] You might want to look up faerie gardens. Faeries live in nature so many who work with faeries make gardens exclusively for them [many will leave a spot on their property to grow wild and they never touch because it's exclusively for fae] look up flowers that attract butterflies and hummingbirds, that along with saffron and some colourful little decorations for them. Wind chimes and 'faerie orbs' are common decorations. Leave offerings of honey, milk, or home made items for them, and try meditating near or in the garden.
I suggest finding a book not only on faerie lore but working with faeries on a spiritual level [research the author first to make sure they're reputable] while I don't work with faeries, I have met a couple, be nice, and if they want to leave, thank them and let them go, otherwise you might get cursed by a fae if you upset them [and before you ask, no, faeries do not physically appear like little winged people, the ones I saw were purple orbs of light]
Fairies are merely a term for spirit. They are spirits of all kinds, ranging from land-wights of nature in an animistic context, to shades of the dead (they are intrinsically linked to the underworld or Elphame, and burial mounds), to the luminous watchers (otherworldly beings that teached mankind), to the goblins of homes (house spirits).
They are not the victorian concept of tinkerbells. They are beings that are above human morality, and easily offended. Many are dangerous and capable of ending lives and worst atrocities. Some find human suffering hysterical, some are violent and amoral, some like to steal children, others love to abduct people.
Take the Slaugh, a scottish fairy composed of a swarm of evil ghosts that grab people and drop them from heights, or the redcap, which chases after people to tear them apart and dye their hats red in the blood. Needless to say, fairies are quite capable of inflicting pain.
They are largely in my view, interchangeable with the spirits of other cultures. The Jinn, Jewish concept of demon (as opposed to the Christian Demon), animistic spirits from many indiginous cultures. Even the practices of the familiar spirit is rooted in animistic fairy lore.
They are repelled by certain herbs, and many of them by cold iron (iron beaten into shape). They operate on laws, and the more powerful ones are deities.
The Folk Devil is one such being in my practice, the Indweller of the wind. I also work with familiars whom are fairies.
I would say that such creatures are mostly good. If a person not irritate them so they do not any damage him.
It is relatively easy to behold them in meditation.
According some mythologies was many of them in a past life people.
Its hard to teach all I know about them in a forum. They are tricky beings, love playing tricks, stealing, and son are actually very mean. They aren't like the ones from tinker bell. They hate being offended. I once had a mark on my ankle from them biting me. Its hard to see them. They are shy and don't like humans much. I see them since I'm really young. They are like energy, that's why we cant see them often. They are nature spirits, they can talk to trees and animals and heal all nature. They like hippies (like me) treehuggers, eco friendly people. They believe that if there's a certain person who doesn't understand and thinks they grant wishes, or a person who doesn't believe in them then they will not wafte their time showing themselves, and even then if they did show themselves a non believer would rarely see them. Mail me if you wanna know more!