Item from harry-potter-prisoner-of-azkaban by
A magical parchment showing every person, passage, room, and secret tunnel in Hogwarts in real time, created by Moony, Wormtail, Padfoot, and Prongs — given to Harry by the Weasley twins this year.
The Marauder's Map was created by Remus Lupin, Peter Pettigrew, Sirius Black, and James Potter during their Hogwarts years — an act of magical cartography so sophisticated it has never been replicated. Fred and George stole it from Filch's confiscated items drawer in their first year and used it for five years before giving it to Harry so he could sneak into Hogsmeade. The Map knows the real identity of everyone in the castle, which is why Harry spots the name 'Peter Pettigrew' moving through the corridors when Pettigrew is supposed to be dead. Lupin, seeing the same name on the Map, realizes the impossible truth. The Map cannot be fooled by Animagus transformations, Polyjuice Potion, or Invisibility Cloaks — it shows what is, not what appears to be. When Snape catches Harry with it, the Map insults him by name: 'Mr. Moony presents his compliments to Professor Snape and begs him to keep his abnormally large nose out of other people's business.'
When blank, it appears to be a worn piece of old parchment. Tap it with a wand and say 'I solemnly swear that I am up to no good' and thin ink lines spread from the point of contact, forming a complete, constantly updating map of Hogwarts. Every corridor, classroom, and secret passage is labeled. Tiny labeled dots move in real time showing every person in the castle. 'Mischief managed' wipes it blank again.
Also known as: the Marauder's Map, Marauder's Map, the Map