Addons in World of Warcraft share a single execution environment. As a result, all Addons have access to the same global variables. If one Addon creates a global variable named "foo", then all other addons can use (or overwrite) that same variable. This allows for some really useful things to happen; the most frequently used tactic that takes advantage of this feature is hooking. Unfortunately, this can also cause some problems in addons. They will conflict if more than one Addon tries to use the same name for a variable. As a result, Addon authors must ensure that their Addons don't conflict by doing one (or more) of the following: