Wikipedia:Tip of the day/May 8, 2006

Transclusion

Including the contents of a template page on a different page (by surrounding the page name with double curly brackets and leaving out the "Template:" prefix) is called transclusion. This allows the other page to be automatically updated whenever the template page is updated. In addition, pages in the following namespaces can be transcluded: Category:, Help:, Portal:, User:, and Wikipedia:. The only difference is that you must include the prefix (followed by a colon) with the page's name inside the double curly brackets. Images also can be transcluded, but this is done using double square brackets instead of curlies. Here are some examples:

{{Pic of the day}} • {{Help:Contents}} • [[Image:Wikipedia-logo.png]]