Fans have created a timeline of the Harry Potter series from one shred of information in Harry Potter and the Chamber of Secrets. At Nearly Headless Nick's deathday party in that book, his death is stated to have been on October 31, 1492. Since the celebration was commemorating the five-hundredth anniversary of Nick's death, this seems to say the scene takes place on October 31, 1992.

However, there are numerous contradictions. For example, in Harry Potter and the Prisoner of Azkaban, Sybill Trelawney refers to October 16 as Friday, but October 16, 1993 was not a Friday. This is usually explained on the grounds of it being simply poetic licence on the author's part.

Another problem involves Nicolas Flamel. Flamel was mentioned as being six-hundred and sixty-five at the time of the first book, but Nicolas Flamel was a real historical figure and wouldn't have reached that age until 1996. The rebuttal for this is that the date the "real" Nicolas Flamel was born, doesn't correspond with the Nicolas Flamel of Harry Potter.

Yet another problem arises from a letter that Harry writes to Sirius Black in Harry Potter and the Goblet of Fire, which contains a reference to Dudley Dursley owning a PlayStation. According to the timeline, this would be in the summer of 1994, but the PlayStation was not released until December, 1994 in Japan and September, 1995 in Europe.

However, this timeline is extensively used by fans and Warner Bros.'s timeline of the series (featured on the DVDs for Harry Potter and the Chamber of Secrets and Harry Potter and the Prisoner of Azkaban) contains dates that were concluded from this dating system (such as Harry's birthday being on July 31, 1980 and his first defeat of Voldemort being on October 31, 1981.) For the sake of convenience, this dating system will be used by the Wikipedia for all Harry Potter articles .

Timeline of the Harry Potter Series

• 382 BC - Ollivander's goes into business making magic wands.

• c. AD 962 - Primitive broomsticks are first used for transport.

• c. 993 - Hogwarts is founded by Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw and Salazar Slytherin. Slytherin petitions to only enroll pure-bloods and, in disgust, leaves the school, but not before building the Chamber of Secrets.

• c. 1294 - The Triwizard Tournament is established.

• 1473 - First Quidditch World Cup is played, during which all 700 Quidditch fouls are committed.

• 1492 - Nearly Headless Nick dies on October 31 from being partially beheaded.

• c. 1840 - Albus Dumbledore is born.

• c. 1920 - Minerva McGonagall is born on October 4.

• c. 1927 - Tom Riddle, who will one day become known as Lord Voldemort, is born to a Muggle and a witch. His father leaves his wife and she dies giving birth to her son. Riddle is raised in an orphanage.

• 1942 - Tom Riddle opens the Chamber of Secrets and frames Rubeus Hagrid for the attacks. He murders his father and grandparents (from his father's side of the family).

• c. 1960 - James Potter, Lily Evans, Sirius Black, Remus Lupin, Severus Snape and Peter Pettigrew are born.

• c. 1970 - Riddle resurfaces, calling himself "Lord Voldemort," and begins his quest for power and immortality.

• 1971 - James Potter and company start Hogwarts. Bill Weasley is born on November 29 to Arthur and Molly Weasley.

• 1973 - Charlie Weasley is born on December 12 to Arthur and Molly Weasley.

• 1976 - Percy Weasley is born on August 22 to Arthur and Molly Weasley.

• 1978 - Fred and George Weasley are born on April 1 to Arthur and Molly Weasley.

• c. 1979 - Sybill Trelawney predicts Voldemort's downfall. Hermione Granger is born on September 19 to Muggle dentists.

• 1980 - Ron Weasley is born on March 1 to Arthur and Molly Weasley. Harry Potter is born on July 31 to Lily and James Potter.

• 1981 - Ginny Weasley is born on August 11 to Arthur and Molly Weasley. Harry defeats Lord Voldemort, and is left with a lightning-shaped scar and the Dursleys.

• 1991 - Harry Potter, Ron Weasley and Hermione Granger start at Hogwarts.

• 1992 - Harry foils Voldemort's plans to steal the philosopher's stone. Ginny Weasley opens the Chamber of Secrets under the influence of Tom Riddle's diary.

• 1993 - Harry saves Ginny and defeats the memory of Tom Riddle. Sirius Black escapes from Azkaban.

• 1994 - Harry learns of Sirius' true colours and Peter Pettigrew escapes. The Triwizard Tournament is held for the first time in centuries.

• 1995 - With the aid of Pettigrew, Voldemort is restored to full power.

• 1996 - Voldemort fails to recover the Prophecy from the Department of Mysteries, due to the efforts of Harry and company. Harry learns of Professor Trelawney's prediction. Sirius Black falls through the veil and dies.