Horcrux

A Horcrux is an object of extremely Dark Magic. Described in Magick Moste Evile as "the wickedest of all magical inventions", it is defined as any object which contains a part of an individual's soul. The first Horcrux ever created was done so by Herpo the Foul.

Nature of a Horcrux
The book Secrets of the Darkest Art, in the Hogwarts Library, gives explicit instructions on creating Horcruxes. The creation of the Horcrux is known to involve a spell, and a horrible act. To split one's soul, one must also commit the most supreme act of evil - murder - and then encase a portion of their fractured soul into a chosen object. The chosen object is usually one of great signicifance or importance, as this act can only be reversed through acts of remorse that are physically very painful.

The process violates two laws of nature and common human decency laws. The first is that mankind must not commit such acts upon one another. The second is that one's soul must remain whole and intact. For these reasons, the Horcrux is the most unnatural and darkest of magical objects. What's more, the subject of Horcruxes is banned at Hogwarts School of Witchcraft and Wizardry. A Horcrux is the opposite of a human being, in that the piece of soul depends upon its container to survive. Destruction of a Horcrux is difficult, but not impossible, and requires that the object be damaged beyond magical repair. One of the most foolproof methods of destruction is Basilisk venom. Very few other methods work, such as through a magical smelting procedure, such as with Fiendfyre.

Albus Dumbledore, Ronald Weasley and Neville Longbottom used Godric Gryffindor's sword to destroy the Gaunt's Ring, Salazar Slytherin's Locket and Nagini respectively. This was only achievable as the sword was made by Goblins; Goblin-made artifacts can be imbued with certain qualities, so when it was impregnated with Basilisk venom when Harry Potter stabbed the Basilisk in the Chamber of Secrets, it became capable of destroying all the Horcruxes.

Horcruxes can also be enchanted to provide some line of defense against destruction. For instance, a spell that makes the object appear too beautiful to destroy, instilling the attacker with great fear and despair, or even direct violence against the attacker.

Horcruxes of Lord Voldemort
Lord Voldemort, obsessed with immortality, went further than any wizard known to history to create seven (although he actually had an eight-part soul) seperate parts of his soul. As a student named Tom Marvolo Riddle, he learned of Horcruxes from some source (most likely the library books of Hogwarts) during his tutilage at Hogwarts, and sought out Potions Master Horace Slughorn for further information. At some point after that, Slughorn informed Dumbledore of their discussion, and gave him a partial stored memory of it. After that, all books regarding Horcruxes in the Hogwarts School Library were confiscated and stored in the Headmaster's Office, until Hermione Granger absentmindedly summoned them to her dormitory at the end of the 1996 school year.

Decades later, Dumbledore and Harry Potter embarked on a quest to locate and destroy, in secret, what they believed to be as many as six to seven of Voldemort's Horcruxes.

List of Horcruxes
Although Voldemort had seven Horcruxes, no more than six existed at one time because Tom Riddle's diary was destroyed before Nagini was made into a Horcrux. As Albus Dumbledore stated, using a living being as a Horcrux is a risky business, as the creature could die or be killed and the Horcrux lose its integrity.



Parallels in the Muggle World
However, the concept of a "soul container" is not original to the world of Harry Potter. For example, the legendary undead Lich could maintain immortality by concealing regeneration power in a phylactery. The Russian myth of Koschei the Deathless is another. In Native American folk tales, sorcerers could evade death by sealing their spirit inside parrots, becoming invulnerable until the parrot was destroyed. In Tolkein's Lord of the Rings series, the Dark Wizard Sauron stored his power and ability to maintain physical form in The One Ring.

Behind the scenes

 * J.K. Rowling knows exactly what the process for the creation of a Horcrux is, but is not telling - yet. The information will be included in the Harry Potter Encyclopedia.  She has told her editor what the process is, and revealed that the editor felt like vomiting afterwards.  All she will say is that a spell is involved, and a horrific act is performed.