The term mob (short for mobile or mobile object) is used to refer to a non-player NPC and is common in many MMORPG games. Generally, these are NPCs that are killed for experience, loot, or to complete a quest. They can be hostile or non-aggressive, and are computer controlled. The term orginated in text based games as MUDs (Multi-User Dungeons/Dimensions/Domains). This term should not be confused with the definition of multiple angry people in a crowd or an organized criminal gang.