Anthony commonly states that he originally intended for Xanth to be a trilogy, and after the wild success of the first three books decided to expand the series to nine books. An extremely devoted fan base persuaded the author to continue writing the series, which is now open-ended. He has since declared, in the Author's Notes of Cube Route, that this 27th book ended the first "trilogy" and that he was beginning a new one with the 28th, punning on the fact that 27 is the third power of three, i.e. three cubed.
Each human character in Xanth is born with a unique magical ability, called a talent. With the exception of the curse fiends and the child Surprise Golem (Daughter of Rapunzel and Grundy Golem), these abilities never repeat exactly in individuals throughout the entire history of Xanth (although nearly identical talents show up on occasion.) Though many are limited in scope, (called the "spot-on-a-wall" variety), the series focuses mainly on individuals with "Magician" caliber abilities (one of the criteria for serving as King of Xanth).
In addition to the human characters, Xanth is populated by centaurs, demons, dragons, fauns, gargoyles, goblins, golems, harpies, merfolk, naga, nymphs, ogres, zombies, curse fiends, and other fictional beasts. Though initially introduced as obstacles to the human characters, some individuals from those groups become main characters in later books of the series.
As the series progresses, some of the half-human species are discovered to have the potential to possess magical talents. The centaurs of the primary centaur community, Centaur Isle, exile any centaurs who demonstrate a magical talent (although some centaur communities are more lenient about possession of talent); however, they tolerate talents in "lesser" races such as humans. Goblins and harpies are shown to have the potential to possess half-talents, the complementary half existing in a member of the other species, (i.e., a goblin must team with a harpy for them to utilize their talent); the hostility between goblins and harpies proved a major obstacle to any serious effort by them to work together to develop these potential talents. Other non-human species are also shown to possess potential for talents.
Geographically, modern Xanth resembles the state of Florida. One major exception to this is the Gap Chasm, an enormous canyon a mile wide which completely bisects the country, though the position of the Chasm could technically correspond with the Cross Florida Barge Canal, which, similar to the chasm, is generally forgotten except for those who stumble upon it. The Gap is guarded by a resident dragon, known as Stanley Steamer, and is crossed by means of treacherous bridges. Many of Xanth's other geographical features are puns on those of Florida (for example, Lake Ogre-Chobee and the Kiss-Mee River). The Florida Keys also exist, though they are, in Xanth, actual keys. Other punnish features include the Isle of View ("I love you") and the Centaur Aisle created by a magician from the Centaur Isle. The moon is close enough that flying creatures may land there; one side is sweet and honeyish, the other has curdled and become cheese, because it saw what was happening on Earth and Xanth. Plants may bear fruit of all descriptions (pie trees and shoe trees are common) or they may be carnivorous (such as the tangle trees), making travel in Xanth risky.
Xanth has a connection with the normal world, which is referred to as "Mundania," its people are called "Mundanes". Although any citizen of Xanth can enter Mundania at any time through an isthmus in the northwest, Mundanes enter the isthmus in Xanth from random geographic locations and time periods throughout history. In other words, Xanth does not seem to be a fixed location or time in the mundane world; and the timeline between Xanth and Mundania seems to jump backwards and forwards. For example, within a normal citizen of Xanth's lifetime, an American Mundane from 2008 could walk across the isthmus as well as an Egyptian Mundane from 3,000 B.C.; however, Mundanes seem to have trouble finding Xanth on a consistent basis, making any travel to Xanth a somewhat rare occurrence. Despite these seeming difficulties, Xanth was colonized in several waves by groups of invaders and nomads from Mundania over the course of several centuries. The series ties these colonization events to actual historical events on Earth, most notably the Punic wars.
The Adult Conspiracy is one of the prominent features of the Xanth world. Nearly every book except the very early ones contain references to the Conspiracy and its effects, particularly those novels in which the main characters are children.
At its core, the Adult Conspiracy seeks to protect children from knowledge that could bring them to great harm. The precise age for entering into the world of the adults is age 18, corresponding to the age of majority in most places. The primary principle that inducts children into the Conspiracy is the understanding of the secret of "summoning the stork." In Xanthian terms, "summoning the stork" literally means to put out a call to summon a stork which will deliver to the couple a child. In Isle of View, it is revealed that summoning the stork will release an "ellipsis" (...) into the air to fly off to the stork. This is a play on the joke that all the "adult" things happen after a paragraph ends in an ellipsis. Most inductees actually discover the specifics of the act "by accident" after marriage, or under the influence of a love spring (a magical spring which causes two drinkers, not necessarily human, or even of the same species, to fall madly, and lustfully, in love with one another at first sight).
Other faculties of the Adult Conspiracy include:
It is important to note that there have been occasions when children gained access to the Adult Conspiracy prematurely. One case is that of Jenny Elf, Che Centaur, and Gwenny Goblin, three children who had to be given access to the Adult Conspiracy when Gwenny received a pair of contact lenses that corrected her poor eyesight while giving her the ability to see others' dreams (some of which could contain Conspiracy material). In one rare instance, a little girl was born with the magic talent of immunity to the magical censorship Adult Conspiracy, causing her family much distress. This was remedied with a vial of lethe water which erased her memory.
Curse fiends are a fictional race created by Piers Anthony for the series Xanth. They are one of the earlier races in Xanth and are known for their talent to throw curses at their enemies. They are believed to be the primary cause for several different settings in Xanth: 1) the land of Air, 2) the land of Earth, 3) the land of Fire, 4) the land of Water (also called the Water Wing), and 5) the Void.
The curse fiends in the present day Xanth stay close to their own community where they put on plays. Because of this, they are well known for their acting skills.