Instance dungeon

In MMORPGs, an instance dungeon is a special area, typically a dungeon, that generates a new copy, or instance, for each group that enters the area. This ensures that there will never be competition (kill stealing, spawn camping) over mobs within the instance and that player characters receive a minimum of lag. Instance dungeons may contain stronger than usual mobs and sought-after equipment.

Games that have been known to use instancing include EverQuest, Anarchy Online, City of Heroes, Everquest2, World of Warcraft, Dark Age of Camelot and Guild Wars. This last one uses instancing extensively to help make the product free of monthly fees.

The use of instancing is a hotly debated topic among the MMORPG industry. Brad McQuaid wrote an article on the topic that can be found here: Brad McQuaid on Instancing.