The Map found in DayZ
The Map is a large topographic map of the game world in DayZ.
A map of Chernarus can be found as loot in-game which can then be accessed using the 'M' key by default.
You can also use the Map to mark locations with a double-click of the left mouse button where you want to mark, then labeling it. This can be used to mark where useful supplies, camps, and specific buildings and structures are. One could even go as far as to mark meeting places if a group of survivors wanted to meet up, thus being able to scope out the place beforehand.
There are a few servers that, along with other useful loot, spawn you with a Map. They may either say it in the server name, or it has to be joined to find out.
Maps are one of the most sought after items in the game, as they show the entire game world and can be used to roughly show the players position by cross referencing an in-game landmark like a town, with the same location on the map. Some servers will show the player's exact position with just a Map, thereby making the GPS nearly useless.
Maps paired with a Compass can be very good for town-to-town navigation and can tell you in which direction you're heading. Compasses are also displayed on the map, showing which direction you are facing.
The Map does not take up usual inventory slots, but goes instead into the tool slots below the sidearm slot. However, they use one inventory slot when stored in the backpack.
A Map is an uncommon tool that has a 1.43% chance of spawning in Residential loot piles, a 1.35% chance of spawning in Military loot piles, a 3.55% chance of spawning in Supermarkets and a 3.70% chance of spawning in Deer Stands. These chances are equal to 143 out of 10 000, 27 out of 2 000, 71 out of 2 000 and 37 out of 1 000, respectively.