Horcruxes and objects or living beings with a part of a persons soul in it. This is so that if the actual person with most of the soul dies, or soul is destroyed, some part of them will be living. To create a  Horcrux, you have to murder somebody. Then your soul will rip in two. If you want to make more, you keep killing people. Keep in mind that it is extremely painful to put your soul back together, and the more horcruxes you make, the more unstable the piece of soul inside your body will be.

More info here:

List of known Horcruxes (not in order of dates created)Edit

Nagini (read books 4-7 for info): A snake- Tom Marvolo Riddle

Quirinus Quirrel (read book 1 for info): A wizard; a temporary horcrux- Tom Marvolo Riddle

Tom Riddles Diary (read book 2 for info): Lord Voldemorts Old Diary- Tom Marvolo Riddle

Marvolo Gaunt's Ring (read book 6 for info): Ring of the grandfather of Lord Voldemort- Tom Marvolo Riddle

Salazaar Slytherin's Locket (read book 7 for info): The locket of Salazaar Slytherin- Tom Marvolo Riddle

Helga Hufflepuff's Cup (read book 7 for info): The cup of Helga Hufflepuff- Tom Marvolo Riddle

Harry James Potter (read the chapter 'Kings Cross" in book 7 for info): Made unknowingly by Lord Voldemort when attempting to kill Harry Potter- Tom Marvolo Riddle

Unknown Object: The first horcrux ever successfully made- Herpo the Foul

How to Destroy a HorcruxEdit

It is extremely difficult to destroy a horcrux, as he easiest way to destroy one is stabbing it with basilisk venom. You cannot destroy it by crushing it, breaking it, or any other ways, because you are just destroying the object, not the actual piece of soul. You can also use the Fiendfyre procedure, and in some cases with the Avada Kedavra curse. It destroyed the part of Lord Voldemort's soul in Harry James Potter when attempting to kill him in 1998.