Faeries, or fairies, are part of European folklore connected to many different cultures and religions. The most well-known faerie folklore stems from Ireland, Scotland, Wales, and England, but also have roots in Greek and Arabic mythology. Faeries, or fairies, are mythical beings intrinsically connected with the natural world.

Though interpretations of faerie folklore vary, faeries are often regarded as mischievous in spirit—neither wholly benevolent or malevolent, but prone to trickery and incapable of mortal emotions such as empathy or unconditional love. Many of their interactions with humans are transactional. Bargains with the fae often sound advantageous to humans at first, but ultimately yield unfortunate results. It is a widespread belief that faeries have a weakness to iron.

Faeries can take many shapes and sizes and can be either humanoid or entirely different creatures. More often than not, humanoid faeries are perceived as being ethereal and beautiful, beyond mortal capacities. It is also common for faeries to have extended or near-immortal lifespans worth several human lifetimes. Though there is rarely such a thing as a harmless faerie, there are also more peaceful and benevolent faeries, such as Brownies. Brownies are guardian faeries known for their phenomenal housework, such as cleaning, mending, and cooking. Alternatively, there are many sinister faeries such as banshees, redcaps, and goblins.

In some tales, the fae live underground or in stone hills; in others, they live in separate realms typically referred to as faerie realms (these are sometimes connected to our world via earthen mounds or caves). Time in the faerie realms typically operates differently than in the human realm; one hour in faerie realms may equal a year in the human world. It is widely believed that if humans consume faerie food or drink, they’ll be forever trapped and/or unable to escape faerie compulsion, or “glamour.” Faerie songs and dances are supposedly very hypnotizing, often causing humans to dance until their feet bleed or they die of starvation.

Scottish faeries are unique in that they are split into opposing courts: the Seelie and Unseelie. Both are dangerous and manipulative, but the Seelie Court is most likely to interact with humans and return favors. The Unseelie Court is more inclined to violence and cruelty.

The increasing popularity of faeries in young adult and adult fantasy romance is attributed to bestselling authors such as Sarah J. Maas, Holly Black, and Julie Kagawa. These authors draw from faerie folklore for inspiration, but it is common for depictions of fae to vary widely from series to series.