Template:Purge/doc

produces a link that will purge the page's cache and rebuild it from the wikitext.

Purpose
For efficiency in service, MediaWiki caches pages. Depending on the exact sequence of actions editors follow, one may view an out-of-date version of a given page. This happens most often on heavily-edited pages and on pages which contain an instance of transclusion.

adds to any page a link that, when clicked, not only reloads the page, but clears the server cache, forcing the page to be completely rendered "from scratch". This is not a one-time solution; generally, editing a page is itself sufficient to purge cache. Rather, it is a measure taken in anticipation of the frequent need to purge.

Examples
When you are linking to a section, purging that page will cause you to lose the section link.