In the colossal Harry Potter universe, the Elder Wand is the most sacred and powerful wand a wizard can achieve. As one of the three objects making up the Deathly Hallows, it has been owned and utilized by some of the most capable wizards in the entire franchise. Created by Death itself, the Elder Wand has been around since Antioch Peverell outsmarted Death and requested the wand as a gift.
In Harry Potter and the Deathly Hallows – Part 2, a battle with Draco saw Harry disarm Draco of his wand, and even though it was not the actual Elder Wand, it still meant that Draco was disarmed, thus meaning that any of the wands in his possession were immediately passed to Harry. Moreover, Draco did not realize that the Elder Wand was in his possession. With the Elder Wand’s powers awarded to Harry, the young wizard used it to his advantage during his epic standoff with Voldemort at Hogwarts.
During the battle, when Voldemort attempted to perform the Avada Kedavra curse on Harry, his efforts backfired and he wound up using the deadly Killing Curse on himself. That, and the effort of Neville killing Nagini certainly helped. At the end of the final film, Harry uses the Elder Wand to repair his personal wand and ultimately breaks the Elder Wand in half before tossing it off a bridge. This defining act is different from what happens in the final book, however, as in the Deathly Hallows novel, Harry returns the Elder Wand to Dumbledore’s tomb.
So, why did Harry break the Elder Wand?
When Harry realized that he was the definite owner of the Elder Wand, he also realized that he was in possession of the other two objects that make up the Deathly Hallows: the Resurrection Stone and the Cloak of Invisibility. This made Harry the Master of Death. With this in mind, Harry realized that the Elder Wand produced a certain amount of greed and a desire for ultimate power and he realized that it had to be stopped.
Harry also realized that whoever possessed the wand as its rightful owner would have an abundance of power. Rather than allowing the danger and greed that surrounded the sacred wand to continue, Harry felt that effectively destroying it would make peace within the Wizarding World. Furthermore, he was the only one who could destroy the wand, hence the reason he decided to do so.