This template is used on approximately 290,000 pages. To avoid major disruption and server load, any changes should be tested in the template's /sandboxor/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.
Alternatives
{{Null}} also redirects here. It is also possible to use {{ns:0}}, the empty/void/null string for the main namespace.
It can be used in place of <nowiki /> to break character sequence parsing, for example {{nowrap|{''a''}{{null}}}} to force the first closing brace to be treated as part of the template parameter instead of as the end of the template expression.
