He didn't tell Harry about the Prophecy, because he thought it would affect Harry's peace of mind and happiness , when he comes to know that he's the chosen one and that his parents died due to a prophecy.
Dumbledore knew that destroying Voldemort's horcruxes was the only way to truly defeat him. He believed that Harry was the one person who was smart, courageous, and perhaps lucky enough to find and eliminate all the horcruxes.
Question number one: Why didn't Dumbledore just give the sword of Gryffindor to Harry instead of leaving it to him in his will? He knew even before his death that Harry would need the sword to destroy Horcruxes, and he must have known that the Ministry would not let Harry get the sword.
He didn't tell him, because there was always a possibility of Voldemort peeking in Harry's mind and seeing that piece of information, because if voldy had learned that snape was a traitor, he would have killed him, and hid all the horcruxes into more safe places, that was the same reason why snape didn't gave harry the ...
Dumbledore KNEW that Harry would not die. He knew because he knew that Voldemort had taken Harry's blood. Dumbledore knew because he understood that Lily's sacrificial protection was still in effect.
Draco Malfoy's mother Narcissa was cold, cunning and devoted to the Dark Lord. But she was also a mother, which meant she was willing to risk everything to make sure her son was safe. When Harry survived Voldemort's Killing Curse for the second time, Narcissa pretended he was dead so she could get to Draco.
However, the Hogwarts headmaster was not a comforting character with unconditional love that Harry would want at his side as he died. Rather, as an insightful adviser, Harry had Dumbledore waiting for him in Limbo where he could choose to live or die after being “killed” by Voldemort.
Later in the year, McGonagall duelled with Death Eater Alecto Carrow during the Battle in the Astronomy Tower and later learned of Snape's murder of Dumbledore. McGonagall was initially appointed as Headmistress, but was demoted after Voldemort took control of the school and placed Snape as Headmaster.
But there were parts of the story Harry didn't know, including that Dumbledore was already dying and had asked Snape to kill him when the time was right.
He finds out for sure immediately after Nagini's attack on Arthur Weasley. This night is significant in many ways. While Harry sleeps, he enters Nagini's mind.
Dumbledore reveals how thoroughly he loves Harry. Harry is brave, and Dumbledore is proud as any father would be. More than that, Dumbledore succumbs to a parent's weakness; he cares more about Harry's happiness and wellbeing than the wizarding world he is trying to protect.
“Dumbledore didn't want to lose his wand at that point and Draco disarmed him. So that meant that the wand gave Draco its allegiance, even though Draco never knew it, even though Draco never touched it. “From that moment on, that wand gave its allegiance to Draco, and it wouldn't work as well for anyone but Draco.”
Voldemort intended to make his final Horcrux with Harry's murder, so we can make an assumption that he did the underlying magic to create the Horcrux, so when the killing spell rebounded on Voldemort, the process had been started, but without Voldemort to direct the fractured piece of his soul, it latched itself onto ...
Severus Snape wanted to teach D.A.D.A. for years, but Albus Dumbledore denied him the job repeatedly, partly for fear of Snape straying back towards the darkness, and partly to keep him around for longer, given the curse on the position. Snape finally got his wish in Harry's sixth year, taking over D.A.D.A.
If Voldemort knew Harry was a horcrux he probably would've either convinced Harry to become a Death Eater or torture him into insanity, *Longbottom style*, so he wouldn't kill off a piece of his soul, but could keep Harry to a point where he wasn't a liability to his immortality.
Erroneously believing Snape is the master of the Elder Wand and that Snape's death will make him the master of the Wand, Voldemort kills Snape by having his pet snake Nagini bite him through the neck.
Voldemort intentionally made six Horcruxes, but when he used Avada Kedavra on Harry, he unintentionally created a seventh Horcrux. Instead of dying, Lily's love for Harry created a counter 'curse' known as Sacrificial Protection and saved Harry.
Yes, Dumbledore did ask Snape to kill him so Draco wouldn't. Dumbledore did indeed ask Snape to kill him, so that Draco wouldn't either succeed and maim his own soul, or more likely fail and be killed by the Dark Lord for his almost inevitable failure. "All the same, try.
Knowing that Snape has been on the Dumbledore's side for all seven of the Harry Potter books reveals him as an extremely brave man and a truly skilled spy. Snape has had to face and deceive the terrifying Lord Voldemort constantly.
"I regret it," said Voldemort coldly. When Voldemort finally works out the truth about the Elder Wand (albeit incorrectly) he sends Lucius to fetch Snape and then confronts him before killing him off. He confesses his apparent “regret” for having to kill him, twice.
He has grown afraid of Harry's connection to Voldemort. Perhaps Voldemort, knowing Dumbledore's love for Harry, would possess Harry and provoke Dumbledore to kill him. So, Dumbledore attempted to avoid Harry throughout Book 5 for Harry's own good.
Rowling stated that after his death, Voldemort is forced to exist in the stunted infant-like form that Harry sees in the King's Cross-like limbo after his confrontation with Voldemort in the Forbidden Forest. Rowling also mentioned that, despite his extreme fear of death, he cannot become a ghost.
He was sure there were Horcruxes after laying a eye on the diary (or at least started to think Voldemort might have them). What we, however, do know is that by the time book 4 came along, Dumbledore knew that Voldemort had Horcruxes and he also knew Harry would have had to die - expect this had changed.