Lord Voldemort has six horcruxes which are bits of his soul, separated from the main entity to ensure his immortality.
But if all of them are destroyed, he will be mortal.
His six Horcruxes are:
1. T.M. Riddles Diary
2. Marvolo Gaunt's Ring
3. Salazar Slytherin's Locket
4. Helga Hufflepuff's Cup
5. Something Of Gryffindor's or Ravenclaw's
7. Lord Voldemort himself
the Horcrux, wickedest of magical inventions, we shall not speak nor give direction -
- from the introduction of Magick Moste Evile, Hogwarts Library (HBP18)
Horcruxes are indeed a
matter involving very advanced, very Dark Magic. Only one book in the Hogwarts Library has been found to refer to them even
in passing, the subject is banned at Hogwarts, and only two of the most senior professors on the Hogwarts staff are known
to have any information on the topic: Albus Dumbledore and Horace Slughorn. Most of our information on Horcruxes comes from
them, particularly from Professor Slughorn's memory of a fateful conversation with the young Tom Riddle and Professor Dumbledore's
later analysis of that memory (HBP23).
The term "Horcrux" is used
to refer to any object in which a person has concealed a part of his or her soul. The object need not be inanimate; according
to Dumbledore, a living creature can be used as a Horcrux, although it is risky to do so since the Horcrux in such a case
is something that can move and think for itself, independently of the implanted fragment of soul.
The purpose of a Horcrux
is to protect the given bit of soul from anything that might happen to the body of the person to whom the soul belongs. While
the Horcrux is kept safe, the person will continue to exist even if his or her body is damaged or destroyed.
To create a Horcrux, by
definition the spell-caster must have split his or her soul into fragments, so that one fragment can be implanted within the
Horcrux while the other is retained in the spell-caster's own body. The act of splitting the soul is accomplished by committing
murder, which rips the soul apart. From Dumbledore's remarks about Voldemort's possible planned use of the murders of the
Potters when Harry was a baby and of Frank Bryce's murder in 1994 [Y14], it does not matter whether the victim is a witch,
wizard, or Muggle. According to Slughorn, some spell appears to be involved for the implant process, but Slughorn neither
knew nor wished to know the details (HBP23).