Note: This template is used on a lot of pages. In order not to put too much load on the servers, edits should be kept to a bare minimum. Please discuss proposed changes on the talk page first.
Editing a template causes all pages that use the template to be re-rendered. If the template is used often, this can put a lot of load on the servers since it fills up the job queue.
Keep in mind that templates that are used on file description pages also show up on other wikis.
This page is template-protected from editing to prevent vandalism. Only template editors and administrators can edit it. Get their attention by placing {{Edit protected}} at the talk page.
TemplateData is a way to store information about template parameters (the description of those and of the whole template) for both humans and machines. It is used by VisualEditor and possibly other tools like Upload Wizard.
Existing template documentation
At Wikimedia Commons, it is recommended to use {{TemplateBox}} with either useTemplateData=1 or useTemplateData=only on the /doc subpage and transcluding it with {{Documentation}} into the template. <nowiki>-tags can be wrapped around the arguments, if required, to avoid templates being expanded.
Newly created template documentation and imports
Another option, especially for imported templates, or for users with JSON experience, is placing raw <templatedata>-tags into the Wikitext of the template, as described in various Wikipediae.