[1] Great A'Tuin's sex is unknown to the inhabitants of Discworld (though in The Colour of Magic Pratchett describes the turtle as male),[2] but the subject of much speculation by some of the Disc's finest scientific minds.

The basic unit of Discworld magic is the thaum (from the Greek thauma, marvel), equal to the amount of mystical energy required to conjure up one small white pigeon, or three normal-sized billiard balls.

"Splitting the thaum" revealed that it was in fact composed of numerous sub-particles, called resons ("thingies") which in turn are created from a combination of up to five "flavours": up, down, sideways, sex appeal, and peppermint (parodying the real-world quarks).

In Hogfather, the assassin Mr. Teatime tries to kill the patron of Hogswatch by using an old magic that involves controlling a person with a part of their body (in this case, the teeth collected by the Tooth Fairies), in order to stop children from believing in him, and almost succeeds.

A hero will always win when outnumbered, since million-to-one chances are dramatic enough to "crop up nine times out of ten", but always lose when faced with "a little bald wrinkly smiling man" who is almost always highly trained in martial arts.

In addition to its flatness, Pratchett gives it another principal geographic feature; Cori Celesti, a 10-mile-high (16 km) mountain that lies at its exact centre and is the point of origin for its standing magical field.

In Soul Music, a footnote states various facts of the region: The cabbage has an almost mythic status among the people of the Sto Plains, and is an emblem of its largest and dominant city, Ankh-Morpork, which is located near the northeast of the coat of arms.

While it does not exert any political power over its neighbors, its economic domination of the region (summed up by the phrase, "Attack us, and we'll call in your mortgages") has meant that the smaller cities around it are essentially its satellites.

Across their vast extent, from the Hub to the Rim, they incorporate elements from virtually every noted mountain range of Earth, from the Scottish Highlands (Lancre) to the Himalayas (the High Tops) to Appalachia (Slice).

Portals to various otherworlds dot the range's hidden crevices; "gnarly ground" compresses vast areas of land into tiny patches, and where witches, wizards, and godlike monks alike practice their arts.

In an article in Folklore entitled, 'Imaginary Worlds, Real Stories,' Pratchett writes, "the kingdom of Lancre [...] I suspect is a somewhat idealised version of the little fold in the Chiltern Hills where I grew up, stirred in with the western area of the Mendips where I spent a great deal of my adult life.

Most maps show Lancre as roughly 40 by 10 miles (64 by 16 km), its true area remains unknown – partly because of its mountainous terrain and the fact that it borders on the Ramtops, but also due to the warping effect of high level of background magic.

In keeping with the Discworld's affinity for narrative, Überwald's climate and conditions contrive to fulfill human expectations: for example, Überwaldian thunderclaps occur whenever someone makes a particularly forceful pronouncement.

While there are indeed a number of human barons, they all tend to be uninterested in politics, preferring instead to dabble in experimental surgery and "Meddling In Things Man Was Not Meant To Wot Of," each with the help of their personal Igors.

From the 'Diet of Bugs' (a play on the Diet of Worms) onwards garlic and silver were considered contraband across Überwald until the events of The Fifth Elephant; the undead simply promised they would not be needed.

Some people (e.g. Susan Sto Helit), after carefully studying history books, point out that the Battle of Koom Valley seemed to have been repeated several times.

These enforcements can be very impractical and inconvenient, such as banning chocolate, Borogravia's main export; depictions of living things (apart from the Duchess); babies (this law is usually overlooked); crop rotation; and any means of airborne communications (namely semaphore and carrier pigeon).

The banning of semaphore led to the Borogravians cutting down the clacks towers along the Zlobenian border, which was one of the main causes of war between the two nations (with intermittent conflict going on for so long that no-one can remember why it is actually happening), and the reason for Ankh-Morporkian diplomatic intervention.

However, it struggles to keep up with this demand because of its crippled economy (caused by highly inconvenient "abominations"), and as a result of fighting the country is seriously short of young men, so much that a proportion of its soldiers are in fact women in disguise (see Monstrous Regiment).

Under her rule, innkeepers who were not fat and jolly or inclined to tell jokes were sent to the dungeon, and Genua's ruler, the Baron Saturday, was murdered so that his heir apparent, Ella, could be a neglected orphan, as the tales dictated.

The continent includes the Circle Sea states of Ephebe, Tsort, Djelibeybi, Omnia, and the more rimwards territories of Howondaland, Tezumen Empire, Betrek, Smale, Klatchistan, and Muntab.

The disappearance of the Djel River valley in Pyramids briefly sparked a resumption of hostilities, which mostly involved highly reluctant soldiers hiding in wooden horses, waiting for the other side to take them into the city.

The people are perfectly happy living off the fish and olives farmed by the slaves, or the way Teppic described it in Pyramids, they made wine of everything they could stuff in a bucket and ate whatever couldn't crawl out of one, which gives time for Ephebe's major export: philosophy.

The name "Djelibeybi" is a pun lost on most people outside the UK, South Africa, Australia and New Zealand, playing on "Jelly baby", a popular gummi sweet in those countries.

The joke is compounded when Pratchett says that "Djelibeybi" means "Child of the Djel" (its main river; the line is a parody of Herodotus's famous claim that Egypt was the "gift of the Nile").

Omnia is a desert theocracy ruled by the Cenobiarch, the head of the Omnian Church, from the Citadel in the capital city of Kom (a sort of cross between Qum, Jerusalem and the Vatican).

Before the events in Eric, they worshiped the "feathered boa" Quezovercoatl, a parody of the Mesoamerican deity Quetzalcoatl, who was a junior demon who supplanted the previous Tezumen god, a stick; after manifesting himself to his worshippers, he was revealed to be only six inches high.

Exchange rates between the Ankh-Morpork dollar and the Empire's currency, the rhinu, has never been established because the solid gold coins are worth significantly less on the Counterweight Continent than on the Sto Plains.

A book series known as Dangerous Mammals, Reptiles, Amphibians, Birds, Fish, Jellyfish, Insects, Spiders, Crustaceans, Grasses, Trees, Mosses and Lichens of Terror Incognita extends at least into Volume 29c Part Three, while a list of the harmless ones contains only "Some of the sheep."

They wear a sprig of lilac and gather at the Small Gods Cemetery to honour the Watchmen who fell: Cecil Clapman, Ned Coates, Dai Dickins, John Keel, Horace Nancyball, Billy Wiglet, and (albeit temporarily) Reg Shoe.