December 25 in the Harry Potter world (Merry Christmas!)

• 1991: Harry Potter receives his late father’s Cloak of Invisibility and discovers the Mirror of Erised during a late-night adventure. He also receives the wooden flute from Hagrid that will later help him put Fluffy to sleep.
• 1992: Hermione Granger finishes brewing Polyjuice Potion, which Harry Potter and Ron Weasley use to disguise themselves as Gregory Goyle and Vincent Crabbe and question Draco Malfoy. Hermione’s transformation goes badly, giving her the appearance of Millicent Bulstrode’s cat, complete with a tail.
• 1993: Harry Potter receives a Firebolt broomstick from his godfather and late father’s best friend Sirius Black, which is later confiscated from him by Professor Minerva McGonagall. Professor Remus Lupin is absent from Christmas lunch due to his lycanthropy.  
• 1994: The Yule Ball of the Triwizard Tournament is held at Hogwarts School of Witchcraft and Wizardry.
• 1995: Harry Potter, Hermione Granger, and the Weasleys visit Arthur Weasley at St. Mungo’s.  Hermione, Ron and Ginny Weasley learn that Neville Longbottom’s parents are insane and living at St Mungo’s Hospital for Magical Maladies and Injuries.
• 1996: Minister for Magic Rufus Scrimgeour accompanies Percy Weasley to the Burrow, where he pressures Harry Potter to support the Ministry of Magic. Harry refuses, and confirms his loyalty to Albus Dumbledore.
• 1997: Harry Potter wakes up at the Forest of Dean and recovers from a snake bite from Nagini, with Hermione Granger’s help. Also, Ron Weasley discovers that he can hear bits of his friends’ conversations through his Deluminator, if they say his name.

(Source: holymotherofrowling)