Help:Transclusion/How Transclusion Works

Note: this section is transcluded from Help:Transclusion/How Transclusion Works

To transclude any source page (within a single MediaWiki project, such as en:Wikipedia), include the following code in the target page:

{{SOURCEPAGE}}

Whenever a target page with this code ({{SOURCEPAGE}}) is rendered, the engine will include the entire content of SOURCEPAGE in the target page.

In the example below, let the target page be A and SOURCEPAGE be B. If {{B}} is rendered, the engine will include in that place not the code ({{B}}) itself but the content of source page B (which consists of one word, foo).

The top row shows what the target page renders as, while the bottom row shows the code. Note: foo will not be highlighted nor boxed on the target page.

A typical use case for transclusion would be if you wanted to place the same welcome message on multiple newcomer talk pages.

Transclusion creates a "live" link between the template page and the target page(s) upon which the template's contents should appear. When the template is edited, the rendering of that template on the target pages is updated as well. Let's say you create a (template) page in Wikipedia with your home mailing address and then transclude that template not only on your page, but all your friends' pages, too. Later, after moving to a new house, you then update your address template and the new address will automatically appear on all your friends' pages.

There are further simple examples at mw:Transclusion.

Breaking existing transclusions in a template is called breakage. It is to be avoided if possible, as the breakage will ripple through every target page in which the template (source) page was transcluded.