A diff shows the differences between two versions of a page on Wikipedia. A version of a page is created every time someone clicks on Save page after changing it. Another word used instead of version is "revision". Each revision has a time and date when it was made. This is shown in the history of the page. A diff lets you see what changed between two revisions of the same page.

There is a link to see the diff for every revision in the page's history, and similar links in the list of changes made by a specific user, in the list of all recent changes made to wikipedia, and in user watchlists.

This is what a diff looks like. A diff is useful because it makes it easier to see what changes have been made. It also allows to undo the change, or click on various links, for example to put a message in the talk page of the user who made the change.

Revision as of 22:32, 3 August 2003 (edit) Tim Starling (talk | contribs) (Edit summaries in diffs are great) ← Previous edit		Latest revision as of 00:10, 18 August 2003 (edit) (undo) (thank) Angela (talk | contribs) m (correction, + MediaWiki User's Guide)
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	For sysops and those with the rollback flag, a [[en:Wikipedia:revert|rollback]] button is shown allowing them to revert from the new version to the old one.		For sysops and those with the rollback flag, a [[en:Wikipedia:revert|rollback]] button is shown allowing them to revert from the new version to the old one.
−	This is only shown when viewing the diff between the current version and the one immediately preceding it.	+	This is only shown when viewing the diff between the recent version of a page and the last version by an author other than the one of the most current version.
	This example shows the top of the diff page, with the links described above.		This example shows the top of the diff page, with the links described above.
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	</table>		</table>
		+	[[MediaWiki User's Guide]]
		+