The core fae rules are simple: do not thank them, do not give your true name, never eat their food, carry iron and salt, and mind thresholds and twilight. Some are genuinely old Irish and Scottish tradition. The rigid never say thank you rule, though, is largely a modern retelling, not ancient law.
Every few months a thread goes around promising the complete etiquette for dealing with fairies, and the list is always confident and almost never sourced. I am Edmund, and sorting the old bones from the new paint is exactly my kind of afternoon. Some of these rules have walked out of medieval Ireland intact. Others were stitched together on the internet in the last fifteen years and are no worse for it, as long as we are honest about which is which.

The Irish and Scottish roots of fae etiquette
They come from a genuine body of Irish and Scottish belief about the Aos Si, the fairy folk who, in the old telling, were the Tuatha De Danann driven under the hollow hills after their defeat by the Milesians. This was never whimsy. Rural people treated the Good Folk as real neighbours who could bless a farm or blight it, and the etiquette grew from fear as much as respect. One rule almost everyone forgets is the oldest of all: you did not call them fairies to their face. You said the Good Folk, the Fair Folk, the Gentry, or simply Themselves, because naming them plainly was thought to draw their attention. That habit of careful euphemism is well documented and tells you everything about the spirit of the rest. Telling the genuinely old from the newly minted is most of what I do, and how I work with omens and the old protective crafts is on my advisor page.
Why do you never say thank you to the fae?
The usual explanation is that saying thank you admits you are in the fae's debt, or worse, implies their gift was so small that mere words could repay it, either of which gives offense. It is a tidy piece of logic. Here is my honesty clause, though: this specific rule has thin roots in the old collections. You will not find a strong medieval source insisting on it. What you do find is a broad, genuine principle that debts and obligations to the fae are dangerous, and the modern thank you rule is a clean modern crystallization of that older worry rather than an ancient commandment. The traditional advice was less about the word and more about never accepting a gift you had not thought through. So if you enjoy the custom, keep it, but know you are practicing a young rule wearing an old coat. If a genuinely strange encounter is what brought you here rather than curiosity, our live psychic chat guide lays out what a session with a reader involves and what it runs.

Which fae rules are genuinely old, and which are modern?
Here is how I sort them after years with the sources. Genuinely old and widely attested: the horror of cold iron, which is why horseshoes hung over doors and iron was laid in cradles to guard against a changeling; salt as protection, along with the motif that spilled salt or seeds must be counted, keeping the folk busy till dawn; the danger of eating fairy food, which could trap you in their world the way a mortal who ate in the hill was said never to return; and the peril of liminal times and places, dusk and dawn, Samhain and Beltane, thresholds and crossroads, where the two worlds thin. Leaving offerings of milk and bread is old too. More modern, or at least modern in their rigid form: the strict never say thank you rule, and the gaming-flavored idea that a fairy who learns your true name owns you outright, though the older belief that names carry power is real and cross-cultural. If protective folklore interests you, our guides on the acorn protection superstition and on black salt protection show the same instinct in other traditions, and the wider ancient wisdom hub collects more.
If you would like to feel out which old current pulls hardest in you, the seeker quiz is a light free next step, and you can always talk it through with a reader who treats these old customs seriously. For anyone who would rather talk a strange experience through with a person, our live psychic chat guide walks through how that goes.

What should you say instead of thank you to the fae?
The folk workaround, where the custom is kept, is to express warmth without the word: I am grateful for this, that was kindly done, or simply naming the pleasure without the transactional thanks. Some leave a return gift, cream, bread, a bright coin, on the principle that a balanced exchange beats a spoken debt. Notice this is really about reciprocity, which is the genuinely old idea underneath the young rule.
Why leave offerings if you are trying to avoid the fae?
Because the old relationship was not avoidance, it was appeasement. A saucer of milk or a bit of bread left at the hearth or by a fairy tree signaled respect and kept the Good Folk well disposed toward the household. It was insurance, not friendship. The same farmer who left milk out would also hang iron over the byre door, courtesy and defense held in the same hand.
Are the seelie and unseelie courts real folklore?
Yes, and specifically Scottish. The Seelie (blessed) and Unseelie (unblessed) courts appear in Lowland Scots tradition as a rough division between fae who might help or merely prank and those who meant real harm. Modern fantasy has elaborated the two courts far past anything in the old sources, so the bones are authentic even where the newer novels have added a great deal of flesh.
One last folklorist's aside worth keeping. The most reliable rule in the whole tradition was never a rule about thanks or names at all. It was the simple discipline of not naming the Good Folk carelessly in the first place, the reason they collected so many soft nicknames. We called them the Fair Folk so they would not hear us calling them anything, and that quiet piece of etiquette really is as old as the hills they went under.