A null edit occurs when a page is saved without making any changes at all to the wikitext. This is useful for refreshing the cache. A null edit will not register as an edit and will not create an entry in the page history (or in Recent Changes, etc.), so any edit summary provided by the user will be discarded.
The most useful side-effect of a null edit is that it updates category pages, taking into account categories transcluded via templates. If a category has been added to or removed from a template since it was last transcluded on a page, then purging the cache will not update the category contents, but a null edit to the page (not the category) will – see how to add a category by using a template.
Examples of null edits
- Opening the edit window and immediately saving
- Doing this to a section instead of the entire page is sufficient to constitute a null edit, but can sometimes accidentally result in a dummy edit with an empty edit summary.
- Providing an edit summary without changing the page text at all
- This is also a null edit. It's a good idea to always provide an edit summary such as "null edit" and mark the edit as minor, just in case it shows up in the page history.
- Adding newlines only to the end of the page
- This is also a null edit, because such newlines are ignored (stripped away) when the page is saved. Note that this true even when editing a section of a page.