Editing WoW:UI beginner's guide (section)

=== The user's point of view ===
From a user's point of view, what you need to know is that AddOns come in the form of one or more text files, ending in the ".toc", ".xml" and ".lua" extensions. These files are supposed to go into a folder called Interface in your World of Warcraft folder, or into one of its sub-folders. Usually AddOns are distributed as zip files by their authors, and you "install" them by simply unzipping them in your World of Warcraft\Interface folder.

''Warning'': Be very very careful with AddOns that come as executable ".exe" files. Always triple-check before you use these to make sure that they really do what they say they do, as executable files can do anything whatsoever to your computer. AddOns are supposed to be written in text format in .xml and .lua files, so that anyone can check that there is nothing malicious about them. You have no such check available with executable files. Also, since AddOns only operate within WoW, they can't harm your computer, whereas executable files can.

Having said that, some authors ''do'' distribute their AddOns as executable files. Most of the time these executables don't do any more than just unzip the AddOn's files and place them in your WoW folder in the appropriate places. Occasionally the executables are used to automatically download updated versions of the AddOn, or to upload data collected by the AddOn (for example item statistics to be put on a web-site, etc.).

'''Uninstalling''': You can always uninstall any AddOn and reset the WoW UI to its clean default state by merely deleting or renaming the Interface, WTF, and Cache folders in your WoW folder, then restarting WoW.