Help:Reverting

To revert is to undo all changes made after a certain time in the past. The result will be that the page becomes identical to how it used to be at some previous time. A partial revert undoes only some of those changes.

How to revert
To revert a page to an earlier version:
 * Go to the page you wish to revert, click on the History tab at the top or side of the page, then click on the time and date of the earlier version you want to revert to. (It will not work if you click on 'cur', 'last', or "Compare selected versions".)
 * When the page displays, text similar to this: (Revision as of 23:19 Jul 15, 2003), will display. It appears below the page's title, in place of the From {project name}, usually seen.
 * Verify that you've selected the correct version, then click a link to edit the page as you would normally.
 * You'll get a warning, above the edit box, about editing an out-of-date revision.
 * Ignore the warning and save the page. Be sure to add the word "revert" (or "rv") to the edit summary, along with a short explanation if not obvious.

Reverts and edit conflicts
Reverts never cause an edit conflict - if between you pressing edit, and then pressing post, someone else edits the page, their edits will be silently overwritten (though still in the page history). Beware of reverting high-traffic pages! Conversely, if it looks like someone has deleted your edits, consider if it's more likely that it's one of these unfortunate revision conflicts.

Admin-only "rollback" link
On a user contributions page an administrator has additional "rollback" links for contributions marked top (the last edit made by anybody to that article). The diff page, showing the difference between an old and the current version of a page, also has this link. Clicking on the link reverts to the last edit not made by the user being reverted. The feature is especially useful in the case of a known vandal, whose edits don't need to be checked before being reverted. An automatic edit summary, Reverted edits by X to last version by Y, is added. This feature cannot be used when the last two edits were by the same user, and one wants to revert to the previous version only.

If between loading the User Contributions page and pressing rollback, someone else has edited or rolled back the page already, the message Rollback failed will display with an explanation of the problem.

If the page has been created by a malicious user and nobody else has edited the page, clicking the rollback link gives the message Cannot revert edit; last contributor is only author of this article. In this case delete the page, or replace the content with something appropriate to the page name if possible.

Undo
Instead of removing all changes after a certain version, the latest versions of MediaWiki allow a single edit to be undone. To do this, view the diff for the edit, and click on 'undo' above the newer version. The software will attempt to create an edit page with a version of the article in which the undone edit doesn't exist but all later edits are retained. The automatic edit summary added when using the undo feature can be found at MediaWiki:Undo-summary.

This feature removes the need to manually redo useful changes since the "undone" edit. However, it will fail if undoing the edit would conflict with later edits. For example, if edit 1000 adds a paragraph and edit 1005 modifies that paragraph, it will be impossible to automatically undo edit 1000. In this case, you must determine how to resolve the problem manually.