Wikipedia
A mini-map or minimap is a miniature map that is often placed at a screen corner in video games to aid players in orienting themselves within the game world. They are often only a small portion of the screen and thus must be selective in what details they display. Elements usually included on Mini-maps vary by video game genre. However, commonly included features are the position of the player character, allied units or structures, enemies, objectives and surrounding terrain.
Mini-maps have become very common in real-time strategy and MMORPG video games because they serve as an indication of where the current screen lies within the scope of the game world. Most first person shooter games also have some version or variant of the mini map, often showing enemies in real time.