4 Privet Drive, Little Whinging, Surrey is the address for the Dursleys' house in the Harry Potter books. Surrey is a real place, but Little Whinging is fictitious.
The Dursleys are Petunia the mother, Vernon the father, and Dudley the obnoxious son. They were living in this "perfectly ordinary, thank you very much" house for some time before November 1, 1981. That year they had a one-year-old boy named Dudley. On that date, Vernon Dursley noticed a lot of weird things going on in town, and the next morning he and Petunia found their nephew, Harry Potter, on the front step.
The Dursleys thought if they kept Harry as downtroden as possible they could squash the magic out of him. They were unsuccessful. They fled the house in order to escape the letters that Harry was receiving from Hogwarts, which were telling him how to enroll for his first year there. The Dursleys returned to their house, and Harry spent the last month before Hogwarts at their house.
The next summer Harry returned, and on Harry's birthday, the Masons came to the Dursleys' house for dinner. Vernon wanted to make a giant deal with Mr. Mason. Harry was to spend this time in his bedroom pretending he didn't exist. However, Dobby showed up and warned him not to return to school. When Harry refused, Dobby dumped Mrs. Dursley's pudding using a Hover Charm. Believing it was Harry, the Ministry of Magic sent a letter telling him that if he did any more magic outside of school, he would be expelled.
When the Dursleys learned that Harry wasn't allowed to use magic outside school, they realized they could lock him up and he would never be able to get out by magic. Harry was rescued by Ron, Fred and George.
The next summer, Dudley's Aunt Marge showed up. Harry and Vernon made a deal that if Harry acted "normal" then Vernon would sign Harry's permission slip letting him go to Hogsmeade, a town outside of Hogwarts which the students enjoyed visiting several times each term. However on the last night, Harry blew up at Aunt Marge and ran away. The Dursleys said they would let him return next summer, if he stayed at Hogwarts for the Christmas and Easter holidays.
The next summer, the Weasleys came to Privet Drive to pick up Harry and take him to the Quidditch World Cup. Dudley ate one of Fred and George's Ton Tongue Toffies that blew up his tongue.
Two summers later, Harry encountered two Dementors and saved himself and Dudley from them. The Dursleys were ready to throw Harry out, until a mysterious Howler arrived with the message, "Remember my last, Petunia."
