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, and unlike "commenting out" with <!-- -->, 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 them with ^|, so the template name becomes 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 wikisource 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.