Before the First Book
Late at night on July 31st, 1981, the Dark Lord visited the house inhabited by the Potter family and their cat with the intention of murdering Harry Potter.
As he creeps into the upstairs bedroom, Lily Potter, mother of Harry Potter, realized that someone is in the bedroom. She discovered that it was the most dangerous Dark wizard of all time, and he was going to murder her son!
As the Dark Lord raised his wand, she stood in front of the crib. Soon, her husband James Potter rushes to the scene.
The Dark Lord utters the Killing Curse and there is a green light being emitted by his wand. Soon, Lily and James Potter are dead, and their son is alive.
But the Dark Lord created a lighting bolt shaped scar on Harry Potter's head. This scar contained some of the Dark Lord's magical power. But it also contained a fragment of his soul. Yes, the Dark Lord had turned Harry Potter into a horcrux, but he wasn't aware of this.
The First Book
Even later at night on July 31st, 1981, an orange tabby cat sits on a brick wall.
Albus Dumbledore, deceased headmaster of Hogwarts, goes up to the cat. The cat turns into Minerva McGonagall, head of Gryffindor house.
Then, a flying motorcycle emerges from the sky. Its rider is none other than Rubeus Hagrid, half-giant, gamekeeper for Hogwarts Quidditch, and the teacher of Care of Magical Creatures at Hogwarts. In his very large hands is Harry Potter.
He gives Harry Potter to Dumbledore who leaves him on the doorstep of a muggle family named Dursley.
Harry Potter's Future Life
The Dursley family leaves Harry Potter in a small room below the stairs. They do not celebrate his birthday and Vernon, the father of the family, often gets angry at him.
But why do they do this?
Well, the negative energy of Harry Potter the horcrux made the Dursleys dislike him.