Instances are places where a
group (The amount varies) of players. Within the group, there
must be at least
one party present. A
party is sort of like a World of Warcraft "unit" for a
5-man group of people. Inside an instance, the usual objective of it is to kill the last boss, but like the amount of people in a group, it can vary.
The basics are that an instance
must have at least 2 bosses, either made faced through hack-and-slash, where players must kill monsters to get to the boss, or through spawning, where the boss will be spawned after either something has been done such as players arriving at the boss site or unlocking something, or after a certain time. A perfect example of a hack-and-slash instance is
The Botanica which are also another perfect example of in-instances quests. A perfect example of a spawn instance is the
Trial of the Champion, which is a sort of a fusion between an arena and an instance.
There are a few types of instances such as
timed instances, where a
party must complete the objective of the instance within a certain amount of time. An
epic instance where the instance is usually [/b]very difficult[/b]. There are many more types out there. You can even create your own type of instance.
Instances also must sometimes be [n]unlocked[/b]. Locked instances cannot be entered unless
one or more player(s) in (a) party(ies) has either the required item to unlock the instance or has completed a
very long and difficult quest chain in order to gain assess to the instance. A perfect example of both would be
Karazhan where players would have to complete
this quest chain in order to get
this item