The Fae are called numerous different names, such as the Wee Folk, Tylwyth Teg, Faeries, the Fair Folk, and others. One of the reasons they are called by so many different names is because of how many various cultures' folklore they have been a part of.
There are many types of Faeries. Provided below is a short list, though there are many other Faeries.
Boggarts--"evil" household Faeries. A Brownie will turn into a Boggart if angered.
Brownies--household Faeries. Good tempered and kind.
Elementals--Gnomes (Earth), Salamanders (Fire), Undines (Water), and Sylphes (Air).
Knockers--underground Faeries who live in mines. Some believe Knockers to be helpful, while some believe they are manevolent.
Leprechauns--mischievous Faeries in Irish folklore.
Phookas--shapeshifting pranksters. Some believe there is only one Phooka, others believe in more than one.
Pixies--small, mischievous Fair Folk.
Redcaps--murderous Faeries who dye their caps with their victims' blood.
Sprites--small, winged Fae.
Will o' the Wisps--floating lights. Some people believe these are Spirits or Ghosts rather than Fae.
As stated above, this is only an extremely short list of Faeries. There are many others.
Portrayal of Fair Folk often makes them seem a bit mean, if not downright evil. It is important to remember that the culture of the Fae is very different from ours. What seems evil to us may be completely normal to them, and vice versa.
The Faeries' Sabbat is Beltaine. Similarly to how the veil between the the Dead and the Living is thinnest during Samhain, the veil between the Faeries' world (often called the Twilight Realm) and our world is thinnest during Beltaine. Because of this, many people will set out offerings for the Fae on Beltaine. The most common offerings are blood, milk, and small bells.
There are many different spots in our world that are associated with the Fair Folk. One of the places that most people know of are Faery Rings. Generally a ring of mushrooms, there are many stories in folklore about the Fae and these rings.
Though there are a few stories about Faery Rings being lucky, the general consensus is that one should never enter one. It is often said that one will get trapped in the ring, or keep dancing in it until death comes by exhaustion. In fact, there is an old Scottish rhyme that warns of the dangers of Faery Rings:
"He wha tills the fairies' green
Nae luck again shall hae :
And he wha spills the fairies' ring
Betide him want and wae.
For weirdless days and weary nights
Are his till his deein' day.
But he wha gaes by the fairy ring,
Nae dule nor pine shall see,
And he wha cleans the fairy ring
An easy death shall dee."
Another place associated with Faeries are crossroads. In fact, crossroads are said to be swarming with all things supernatural, such as Ghosts, Spirits, Daemons, and even the Devil. Hecate, the Greek goddess of magick and Witchcraft, is also the goddess of crossroads.
Since some mythology says that the Fair Folk can and will do harm, there are many ways to keep them at bay. Some common methods are as follows:
Turning one's clothes inside out, and/or wearing one's clothes backwards.
Iron is believed to hurt the Fae.
Hanging an iron horseshoe over a doorway keeps the Fair Folk out of the house.
Simply avoiding places the Fae go--not following a Will o' the Wisp, for example, or not stepping into a Faery Ring.
Despite some people wanting to ward off the Fair Folk, some paths believe that one can work with the Fae. People can set out offerings to the Faeries, as well as invite them to aid in magick working. If you believe you may have a Brownie or other house Faery or Spirit in your home, set out some milk!
I already knew most of the things written in this article, as I have been studying the Fae since seventh grade. However, I did find the Scottish rhyme online. The link is pasted below.