This template is used in system messages. Changes to it can cause immediate changes to the Wikipedia user interface. To avoid large-scale disruption, any changes should first be tested in this template's /sandbox or /testcases subpage, or in your own user space. The tested changes can then be added in one single edit to this template. Please discuss any changes at the talk page before implementing them.
For efficiency in service, MediaWikicaches 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 Depending on the exact sequence of actions editors follow, one may view an out-of-date version of a given page.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.
{{Purge}} 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.