Editing Help:Substitution (section)

== When to use substitution ==
Generally speaking, templates are [[Help:Transclusion|transcluded]] rather than substituted, although there are some that are specifically designed to be substituted (and may not work if transcluded). Some reasons for substituting templates include:
* making the resulting page independent of future changes to the template
* enabling other automatic replacements to occur (for example, a template may contain four tildes, which will be replaced by the user's signature and timestamp provided the template is substituted)
* enabling the page to be copied to another project without copying the template
* making page rendering faster for the server
* making the correspondence between wikitext and rendered page easier to understand (the opposite may also apply)

Disadvantages of substitution may include:
* Updates to the template will not be reflected on the target page
* The resulting wikitext is longer and more complicated
* Other users cannot see that the text was produced using a template (and will not learn to use the template)
** Many templates add a hidden comment such as <code><nowiki><!-- Template:Foo --></nowiki></code> to the end of their output to mitigate this issue.

Time-dependent variables are substituted to make the rendered page independent of the time at which it is viewed. Substituting page-dependent variables makes the resulting wikitext independent of renaming of the page and of copying to another page.

For more detailed guidance, including lists of templates which should or should not be substituted, see [[Wikipedia:Substitution]].