Templates are a very powerful feature of MediaWiki, but can be confusing to new users and even experienced users can have difficulty making sense of the more complex ones. Templates should therefore be accompanied by documentation to improve usability.
Template documentation should explain what a template does and how to use it. It should be simple enough that a user without complete knowledge of the intricacies of template syntax—which includes many experienced contributors who focus their attention elsewhere—can use it correctly. This is especially true in the case of very widely used templates.
Editors should defer to official policies or guidelines when template documentation pages are inconsistent with established community standards and principles. Editors should also avoid "quoting" template documentation pages as though they are policy—including this how-to guide. Template documentation pages can be written without much—if any—debate, as opposed to Wikipedia policies that have been thoroughly vetted by the community (see WP:Local consensus for details).