Including the contents of a template page on a different page (by surrounding the page name with double braces, i.e. "{{}}" and leaving out the "Template:" prefix) is called transclusion.
This allows the other page to be automatically updated whenever the template page is updated.
Besides templates, pages in the following namespaces can be transcluded:
Category:
Help:
Portal:
User:
Wikipedia:
The only difference between transcluding these and templates is that you must include the prefix (followed by a colon) with the page's name inside the double braces.
Images also can be transcluded, but this is done using double square brackets instead of braces.
To add this auto-updating template to your user page, use {{totd}}
Wikipedia editor
This is a Wikipediauser page. This is not an encyclopedia article or the talk page for an encyclopedia article. If you find this page on any site other than Wikipedia, you are viewing a mirror site. Be aware that the page may be outdated and that the user whom this page is about may have no personal affiliation with any site other than Wikipedia. The original page is located at https://en.wikipedia.org/wiki/User:SummonerMarc.