Template:X0
Template:Void
 | This template is used on approximately 286,000 pages. To avoid major disruption and server load, any changes should be tested in the template's /sandbox or /testcases subpages, or in your own user subpage. The tested changes can be added to this page in a single edit. Consider discussing changes on the talk page before implementing them. |
This template does nothing visually. Technically, it throws away its parameters and outputs the null string.
It is useful for programming advanced templates, and is often used within a template to the right of an equals sign. It may also be used in a template to disambiguate parsing of braces.
It can also be used to temporarily disable code. Unlike "commenting out" using HTML <!-- -->, it nests. This means that {{void|foo {{void|bar}} baz}} is valid, whereas <!-- foo <!-- bar --> baz --> will produce baz -->.
It provides a particularly concise way of temporarily disabling templates, by prefixing the template name with ^|, making the template name become the (ignored) first unnamed parameter. For example, suppose you have a page {{Under construction}} for several days, and wish to change that to {{In use}} during active editing sessions. Rather than delete the unused template, you can leave both templates in the wikitext and change from {{^|In use|...}}{{Under construction|...}} to {{In use|...}}{{^|Under construction|...}}.
Another possible application would be to temporarily disable an infobox on an article page while a problem with the infobox template itself is resolved.
A deeper no-op is {{subst:void|foobar}} or {{subst:^|foobar}}. It disappears completely upon saving.