The Marauder's Map is a magical map of Hogwarts created by Remus Lupin, Peter Pettigrew, Sirius Black, and James Potter (respectively nicknamed "Moony", "Wormtail", "Padfoot", and "Prongs") while they were students at Hogwarts. During this time, they gained extensive knowledge about the school grounds, such as its various hidden passages, from their frequent night-time adventures together.