User:Sophivorus/sandbox

Global vs cross-wiki
A global module would be a module that lives in a single wiki (or repo) but can be used by every wiki, similar to how files live in a single wiki (Commons) but can be used by every wiki. Global modules do not exist yet and are not possible with current technology. There have been several attempts to get there, but none successful so far.

A cross-wiki module, on the other hand, is a module that exists unchanged in several wikis. Cross-wiki modules are possible and some exist. They can be easily maintained using the Synchronizer tool, so that cross-wiki modules are almost as convenient as global modules would be.

Similarly, a global template would be a template that lives in a single wiki but can be used by every wiki, and a cross-wiki template would be a template that exists unchanged in several wikis. Neither exist, and given the way cross-wiki modules work, neither makes much sense. If a template wants to become cross-wiki, the best approach is to turn it into a cross-wiki module.