Only one chapter left until Sonic kicks in! Trust me, and keep reading.
The knocking continued, and Vernon grabbed the rifle that he picked up on the way to the shack. Suddenly, a giant man with bushy black hair smashed through the door to the shack. The wild-looking man greeted Harry warmly, saying that he hasn't seen Harry since he was a baby. Vernon pointed the gun at Hagrid and demanded that he leave, but Hagrid simply grabbed the gun and bended it effortlessly into a knot before tossing it away. Hagrid then gives Harry a birthday present: a large chocolate cake
Harry was stunned, and he asked Hagrid who he was. Hagrid introduced himself as the Keeper of Keys and Grounds at Hogwarts. When Harry still didn't fully understand, Hagrid explained again that he worked at Hogwarts, assuming that Harry knew about Hogwarts; Harry said that he didn't. Hagrid continued to question Harry, asking if he knew where his parents "learned it all." Harry was still confused, making Hagrid even angrier. Hagrid then turned to the Dursleys and thundered at them, shocked that they hadn't told Harry anything about who he is or about his parents. Hagrid turned swiftly back to Harry and revealed to the young boy that he is a wizard.
Hagrid pulled out a letter, which Harry finally read: it was an invitation to the Hogwarts School of Witchcraft and Wizardry. Harry's head exploded with questions. Hagrid then pulled out an owl from one of his giant pockets and wrote a note to Dumbledore, saying that he has given Harry his letter and was taking him to buy his school supplies the following day. The owl took the note and flew off.
When Hagrid finished, Vernon announced that Harry is not going to Hogwarts. Hagrid said that a Muggle is not going to stop Harry if he wants to go, quickly explaining to Harry that Muggle means non-magic people. Vernon said that when they took Harry in, they resolved to "put a stop to that rubbish." Harry was appalled that they knew he was a wizard all along.