World of Warcraft includes significant support for modifications to the user interface (UI) of a game, colloquially known as "mods" and "addons". At a simple level it allows full control over the content of toolbars and hot keys, as well as macros to automate sets of operations and the ability to script much more elaborate tools. The range of modifications that are available can be anything from ways to automatically advertise trade skills, to adding extra rows of button bars for spells, skills and more, to one designed for humorous intent, such as one that reproduces the infamous Leeroy Jenkins sound. The 2.0 release of World of Warcraft changed the way that an addon interacts with the game, causing certain modifications and addons to no longer function as intended. This meant that all addons designed before the patch needed to be rewritten, or they would not work.

 

Addons in World of Warcraft are coded using one or both Lua and XML, and images used for modifications are created using the .TGA (Targa) and .BLP image formats. Blizzard has also released a User Interface Customization tool to support and encourage UI modders. However, Blizzard is unable to endorse or provide support for third party interfaces due to issues that may be caused by them.

 

Some third-party programs that operate in a stand-alone mode, or independent of World of Warcraft, may be considered exploits, especially if they automate operation beyond that made available using the built-in macro functionality, or pass information in or out of the game. Use of these is against Blizzard Entertainment's Terms of Use. When playing the game, and as such, may lead to possible suspension or closure of accounts. Blizzard has stated on the official forums that any modification that uses the Lua programming language will not be considered an exploit, though Blizzard reserves the right to change information available via the Lua language if the modification changes the nature of encounters in the game.