It was Draco's wand that switched allegiance to Harry at Malfoy manner. Harry did not even touch the Elder Wand until he disarmed Voldemort in their final face-off. It was then that the Elder Wand switched allegiance for Draco to Harry. Remember that Draco is the one that disarmed Dumbledore.
Why is Harry the rightful owner of The Elder Wand?
Nearly a year after Draco had unintentionally become the wand's master, Harry had taken Draco's wand by force during the Skirmish at Malfoy Manor, making him the new master of the Elder Wand.
Why did the Elder Wand belong to Harry and not Voldemort?
Unfortunately for him, he did not have enough information to realize the truth — that Harry was the master of the Elder Wand because he had previously defeated Draco Malfoy, who had previously disarmed Dumbledore.
At the film's end, Harry briefly explained that Snape had never been the wand's master since Draco had disarmed Dumbledore that night. Then, since Harry had stolen Draco's wand in Harry Potter and the Deathly Hallows - Part 1, the Elder Wand's loyalty had transferred to Harry—even without having ever touched the thing.
We know the Elder Wand allied with Draco Malfoy, who disarmed rather than killed Albus Dumbledore. It later switched its loyalty to Harry Potter during his escape from Malfoy Manor. While deaths did occur in both situations (Dumbledore and Dobby respectively), neither Draco nor Harry committed the act.
The Elder Wand Did Belong To Whom ? (Draco? Snape? Voldemort? Or Harry Potter)
What makes the Elder Wand so special?
The Elder Wand was 15 inches long, formed by Death himself, made of elder wood, and contained the center of the tail-hair of Thestral. This core makes a wand much more unique to successfully wield, since only someone who has embraced "death" can even see a Thestral fur, the Elder Wand can be held by very few wizards.
How did Voldemort know Dumbledore had the Elder Wand?
Voldemort broke into the prison Nurmengard Castle, where Gellert Grindelwald was being held, and demanded to know the location of the Elder Wand. It was only during the confrontation in Grindelwald's cell that Voldemort learned Albus Dumbledore had claimed the wand in a duel decades back.
Ultimately, it's a good thing that Dumbledore's plans didn't work out because if Draco hadn't disarmed the headmaster, Harry wouldn't have gained the Elder Wand's power when he later disarmed Draco. This was proof that, unlike Dumbledore, Harry was destined to reunite the Hallows and become Master of Death all along.
He promised to protect Draco Malfoy from harm and guide him whilst he attempted to perform the task the Dark Lord had asked him to do: to kill Albus Dumbledore. Snape was actually a double agent working for Dumbledore, who requested Snape to kill him anyway to spare him of a painful and humiliating death.
Why didn't Snape tell Harry he was protecting him?
Snape even said that he didn't want anyone to find out that he was protecting Lily's child, “especially Potter's son” (pg. 679 of Harry Potter and the Deathly Hallows) because of his hatred for James. Instead of providing Harry a safe haven from his abusive home with the Dursleys, he tormented Harry over an old grudge.
Was Dumbledore only powerful because of the Elder Wand?
Dumbledore possessed the elder wand, but his talent, diligent work and exceptional mind were the only reasons he gained such a reputation and prominence in the wizarding world. A Harry Potter fan who thinks in great detail about the books, and tha Universe. No. In fact the Wand helped him not at all.
The Disarming Charm became Harry Potter's signature spell, and it notably caused the final defeat of Lord Voldemort during the Battle of Hogwarts by rebounding his Killing Curse, because the Elder Wand recognised Harry as its master through the spell connection, and thus strengthened the Disarming Charm to the point ...
Harry was the true master of the Elder Wand at this point. Voldemort began to realize that the Elder Wand wasn't obeying him as it should. He believed that Snape was the true owner since he killed Dumbledore and had Nagini kill him.
Notably, Voldemort appeared to be entirely unaware of this split, as he later created a seventh Horcrux in his quest to have six, and continued to target Harry Potter despite him now holding part of Voldemort's own soul.
His dad gave it to him. To elaborate on Icecreamdif's answer, he inherited it as a family heirloom dating back to Hardwin Potter, who married Iolanthe Peverell, granddaughter of the Cloak's original owner Ignotus. It was passed down to the eldest male of each new generation of Potters since then.
Harry believes that if he dies a natural death while still having the true ownership of the wand its power will be broken and no one will be able to have such power. So Harry uses the wand to repair his original wand and then places the elder wand in Dumbledore's tomb.
Despite her beliefs and her family's close ties to Lord Voldemort and the Death Eaters, Narcissa never joined the organisation herself, nor received the Dark Mark. While she treated most people coldly, Narcissa was very loving towards her family as well as devoted to them.
Family. Snape's family background is mostly shown in flashbacks during the course of the last three novels. Snape was born to Eileen Prince, a witch, and Tobias Snape, a Muggle, making him a half-blood (hence the name, "Half-Blood Prince").
Vulnera Sanentur was the song-like incantation of a healing spell which was used to heal deep wounds, which could also be used as the counter-curse for the curse Sectumsempra.
At the Quidditch World Cup, Draco is quick to sneer at the Trio, and warn them to keep Hermione out of sight - as a Muggle-born, she could well be a target for the wizards rioting and tormenting the Muggle camp-owner.
After seeing how cruelly Draco spoke to his friend, Harry firmly rejects the boy's offer, telling him that he's perfectly capable of telling the wrong sort for himself. In this case, Draco's arrogance reveals that he himself is in fact the 'wrong sort'.
He was tortured by Lord Voldemort for information regarding the twin cores of Harry Potter's wand and his own. Ollivander told him that he merely needed to use a wand other than his own to face Harry Potter.
During his final confrontation with Voldemort, Harry knew that he (Harry) was the Elder Wand's true master. He again cast Expelliarmus, ejecting the wand from Voldemort's hand into his own as the Killing Curse rebounded off his body, fatally striking Voldemort.
The prevailing theory has been that Voldemort gradually lost his nose (and humanity) throughout his life due to his exclusive use of Dark Magic. The more Dark Magic he tapped into, the less human he became both figuratively and literally. This was only amplified as he split his soul to create the Horcruxes.
