What is the stone for in Harry Potter?

Answer 1

There is no such thing in the Harry Potter series.

In the first book we learn about the philosopher's (sorcerer's) stone which produces the Elixir of Life and makes the drinker immortal.

In the seventh book Harry finds out about the three hallows one of which is the resurrection stone that can let you see your deceased loved ones.

Answer 2

There are two main stones in the series, the philosopher (sorcerer's) stone and the resurrection stone.

The philosopher's (sorcerer's) stone is the plot of the first book. This stone produces the elixir of life which can be used to make the drinker immortal. Voldemort attempted to steal the stone and use it to return himself to full power. Harry managed to foil his plan, and the stone was destroyed.

The resurrection stone is one of the deathly hallows. It has the ability to allow the user to speak to deceased loved ones. Owning all three hallows would make you the master of death.

Answer 3

The "philosopher's stone" (or "sorcerer's stone" in the U.S. edition) is used (among other things) to make the elixir of life - to prolong life. That's what Voldemort wants it for.