the object in question is called a horcrux. They are made by murdering someone and then intentionally ripping a piece of your soul off and sticking in an object. So long as that object, or more specifically the soul fragment within it, exists, then you can't actually die even if your body is destroyed.
Naturally, it is advised to protect this object as best you can if you do something so stupid as ripping your soul apart in the name of not dying.
Like seriously, at least liches keep their soul in one piece.
Existing as an incorporeal incomplete spirit is difficult and not fun, and draining in a variety of ways if you aren't possessing a body, but it is technically a form of immortality. Regaining a body is hard.
Voldemort decided to rip his soul into seven pieces, because magically significant numerology. Thus, six horcruxes. The diary he kept as a teen, Ravenclaw's diadem, Hufflepuff's cup, Slytherin's locket, the Gaunt family ring, and his pet/familiar snake Nagini. And also Harry by accident, meaning eight pieces, seven horcruxes.
The diary and ring have already been destroyed. The diadem is in the room of requirement, the cup is in the Lestrange vault in Gringotts, the locket is among the valuables Harry and Taylor just secured, and the snake is with Voldemort.
Perhaps rip is too rough a verb, but let's be honest, splitting your soul into multiple pieces cannot be healthy. Especially if your soul does not heal or regenerate from the damage.