Marauder's Map

From Hpwiki

The Marauder's Map shows a plan of Hogwarts and its environment, including all secret passageways, with small moving dots showing the current positions of specific people. Even should a person be invisible, Polyjuiced or in any other form altered in appearance, still their true name will appear on the map, as evidenced by the confusion about Scabbers and Barty Crouch, Jr..

It was created by Messrs Moony, Wormtail, Padfoot and Prongs. At one point it was confiscated by caretaker Argus Filch who was unable to work out its purpose. Years later, the Weasley Twins nicked it while in Filch's office. In their fifth year they passed it on to Harry Potter.

People wishing to use this map must say "I solemnly swear I am up to no good" to activate it. Failing that, the map might start making fun of anyone trying to discover its secret. The map can be wiped blank again with the code "Mischief managed."