Editing WoW:UI beginner's guide (section)

=== Standalone addons ===

''Standalone, pure AddOns, what is so good about them?''

You will sometimes see AddOn authors being proud of their AddOn being "standalone", or "pure addon". In the past, often AddOns modified existing UI functionality by changing something in the existing, core UI files provided by Blizzard. This has led to conflicts as different AddOns all tried to modify the same file. A "pure addon" is one that does not modify any existing files, and merely adds its own files. This is a very good thing, because you can have any number of such AddOns happily coexisting side-by-side. For this reason in WoW patch 1.10, Blizzard has completely disabled the ability to change the core UI files themselves. Therefore, all modifications to the UI can now only be done via pure AddOns. (Note that this doesn't mean that existing functionality of the UI can't be modified, it just means that it has to be done via an AddOn without modifying Blizzard's files themselves).

Also, a lot of AddOns depend on other AddOns for their operation. For example, most AddOns in the Cosmos package wouldn't work by themselves, and need the whole Cosmos package to be present to work. A "standalone" AddOn is one that is capable of working by itself, with nothing more than just that one AddOn being present. Again, this is a good thing, because it allows you to pick and choose just those exact AddOns that you want, without having anything you don't want. Many addons are aware of the major addon frameworks though and can interact with them if they're present.

Having said that, from the point of view of an AddOn's author, you will find that often a lot of AddOns do very similar sort of things. It is much more easy and quick for an AddOn author to create a new AddOn if they can rely on existing functionality in other AddOns or some common core "libraries". That's why there are AddOns out there that depend on things such as the [[Sea (AddOn)]] function library, which in itself is just an AddOn. If you find an AddOn that requires some other core AddOn, don't be afraid of it. Just make sure you also download the core AddOn.