What is a horcrux?
This word is mentioned in the Harry Potter books. Its means that when you made too much evil , or killed innocent people , your soul is ripped into two. One part of the soul remains inside you, while the other one, you can store in some object, like a can, locket, bottle, just about anything, by casting a spell. You can even store your bit of soul in a living thing. Now the object in which you store the bit of soul is called Horcrux. Voldemort made 7 horcruxes. Six of them were intentional, but when when Voldemort’s killing curse rebounded upon him part of his soul latched onto the soul of Harry Potter, making him the 7th horcrux.
The term horcrux is an invention of J.K. Rowling, first mentioned in the sixth Harry Potter novel, Harry Potter and the Half-Blood Prince. Creating a horcrux occurs when one rips the soul by committing an intensely evil act, such as murder. The portion of the soul ripped away is then encased in some type of meaningful object. Thus, if the physical body of a person with a horcrux were destroyed, the person would still not be dead, unless horcrux containing the piece of soul was also found and destroyed.