A Horcrux is the word for an object in which a person has concealed part of their soul… you split your soul, you see… and hide part of it in an object outside the body. Then, even if one’s body is attacked or destroyed, one cannot die, for part of the soul remains earthbound and undamaged. But of course, existence in such a form…few would want it, Tom, very few. Death would be preferable.
― J.K. Rowling, Harry Potter and the Half-Blood Prince
Meh, I lost mine a long time ago.