As to appearance, the Marauder’s Map would simply appear as a blank sheet of parchment. However, upon activation, it would reveal itself as a magical map which contains details of the interior and exterior of Hogwarts castle, including the names and locations of people inside the castle. People would appear as miniscule dots that move as the real persons travel inside the castle. (hp-lexicon).
The map can be activated by saying “I solemnly swear that I am up to no good.” Thereafter ink lines would appear across it to reveal a very detailed map of Hogwarts. It would show all places inside the castle, including secret passageways. There is only one room which the map cannot show, which is the Room of Requirement. (Answers).
In order not to bring the map back to its original state as a blank piece of parchment, the user must tap the map as say the words “Mischief managed!” Thus, anyone who would come across the map cannot use it and avail of its secret powers. (Rowling).
Map Of Hogwarts Grounds
The map obviously serves numerous functions, foremost of which is to inform the user of necessary information he would need in accomplishing his tasks. The user can instantly know whether there are friends or adversaries to be met along the way, which provides him with opportunity to change course, if necessary. In addition, the map teaches its user of the many secret passageways which are unknown to others who live in the castle. More importantly, the map recognizes real identities of persons, including those who are disguised using the Polyjuice Potion or those who have transformed into Animagus form. It can also look beyond Invisibility Cloaks. (Mugglenet). Thus, there is no escaping the powers of the amazing Marauder’s Map.
If I had a Marauder’s Map, and provided I could use it outside Hogwarts, I would use it to keep track of the locations of people I care about, so I would know instantly if anyone were in trouble. Also, if I want to surprise them, I could always show up unexpectedly. I could also use it to look for alternate routes when there is any kind of trouble with my usual path. However, given the nature of the map, it should not be abused to the extent that people’s privacy would be violated. It should only be used for good-natured purposes. For example, the map can be used as a surveillance tool to locate dangerous people. Also, I can offer its use as a public service tool in searching for missing loved ones.