Instance dungeon

In MMORPGs, an "instance dungeon" is a special area that generates a new "instance" for each group that enters the dungeon. Once your group enters the dungeon, a separate copy of the dungeon is made, such that you are the only players within that instance of the dungeon. Thus the name "instance dungeon". This ensures that there will never be competition over the monsters within the instance.

Instance dungeons generally contain elite monsters with a high degree of difficulty and very good loot! They are instanced so that players don't fight over spawns.