In order to classify the faerie characters in the stories, the race is divided up into two groups: the peasantry and the aristocracy; trooping and solitary. It is a distinction that hold good throughout the British Isles, and is indeed valid wherever fairy beliefs are held.

The peasantry is made up of the solitary faeries that are believed to have descended from spirits who made up all of nature. Although they had some of the same powers as their more prestigious relatives, i.e. the ability to become invisible and shape-change, they were known to be more wild and capricious. Fortunately, true encounters with mortals were relatively rare, instead their presence were most often announced by evidence of the creatures’ activity. It was believed the bending of the grass, the rustling sounds of tree branches, and the glittering patterns of frost on windows could be attributed to their nearness.

The Faerie aristocracy was very different from their isolated cousins. They were known as trooping faeries because they travelled in long processions. The trooping fay can be large or small, friendly or sinister. They tend to wear green jackets, while the Solitary Faery wear red jackets. They can range from the Heroic Faery to the dangerous and malevolent Sluagh. They dwell in underground kingdoms or across the deepest seas. In many cultures like those in Scandinavia and Scotland, they subdivided the aristocracy into good and evil. However, there is no distinction between the good and evil faeries in Wales and Ireland. They were called the Tylwyth Teg (Fair Family) and the Daine Side (Dwellers of the Faerie Mounds) respectively. The Irish have the most complete accounts of the trooping faeries hidden within their many songs and folktales

The second basic classification was between the Seelie and the Unseelie courts. The Seelie, or Blessed, Court was made up of fey who were neutral, or benevolently inclined towards humans, and who represented the powers of regeneration and growth. However, although the Seelie were the 'good' fey, they were believed to be just as capricious and often as amoral as the Unseelie. The Unseelie were the 'bad' fey, those which were malevolently inclined towards humans and represented the powers of death and entropy.

Both courts included both the trooping faeries, also often called elves, and the solitary faeries.

In common usage, 'Seelie' often refers to the trooping faeries of the Seelie court, the benevolently inclined humanoid fey, who should more properly be called Sídhe.

Seelie and Unseelie used in Modern Day Writing.

• The Two Courts are used in the book Tithe : A Modern Faerie Tale by Holly Black.

• The Two Courts are used in the Meredith Gentry series {A Kiss of Shadows, A Caress of Twilight, Seduced by Moonlight, and A Stroke of Midnight} by Laurell K. Hamilton.

• The Two Courts are heavily used in Mercedes Lackey's modern fantasy works (the Bedlam's Bard and SE Edge series).

• The Two Courts are used in the book War for the Oaks by Emma Bull.

• The Two Courts (usually called Summer and Winter but referred to as seelie and unseelie, respectively, at least once) are used in Jim Butcher's series, The Dresden Files, particularly Summer Knight.

• The Two Courts are also used in Gerald Morris's series of Arthurian tales starting with "A Squire's Tale."