Gonna cover the fine details of patrolling edits and using rollback in this blog.
Rollback is an extra user right granted that helps quickly revert vandalism and bad edits. You can find the "rollback" link on both the recent changes log and in the page history of articles. See the image below:
To use rollback you simply click the link. The page reverts to the previous editor's most recent edit. In the example, you see my two edits. If you were to click "rollback", it would revert to Agent c's most recent edit, without having to go through the edit diffs screen. It's automatic. In the next image, you see rollback in use on a page history:
Here, clicking rollback would revert CommanderNuka's edits back to the most recent A Follower edit.
Rollback vs. Undo
Most of the time, you'll want to use the undo feature. Undo allows you to leave an edit summary that will show in the recent changes log. There's a few good reasons for this. First, it allows you to communicate the reasons why you've reverted the edit to those reading the rc log and (hopefully) the editor making the reverted edits. It also allows you to leave a notification message like "Vandal" in the edit summary for admins to pick up on so they can block folks that need a spanking. Rollback should be reserved for when you really need to revert lots of edits quickly, like a spam attack. Please make sure you use "undo", rather than "rollback" unless you really need it.
Rollback doesn't care who's edits its reverting. If you accidentally use rollback on a page that only you have edited, say a sandbox, it will remove all consecutive edits from the most recent editor. If only you have edited a page, it will delete everything. So use it carefully.
Patroller is an extra user right that allows an editor to see which edits have been checked as ok in recent changes. All edits made by patrollers and sysops are automatically marked as patrolled. All other edits are marked with a little red "!". See the image of recent changes below:
You'll see that all the edits with a red "!" have not yet been checked by a user with patoller rights. All those that do not have a red "!" were either made by a patroller or sysop, or have been checked by a patroller and marked as "patrolled". When you click the diff link in recent changes to check an edit, patrollers have a link they can click to mark that edit as patrolled and it will remove the red "!" from that edit in rc. Be advised: You have to check each edit individually. You can't click the diff link for a series of edits to mark them patrolled. You will not get the "mark as patrolled" link.
Communication by log
One important thing to do as a patroller is to make sure you clearly mark vandal edits when you undo them with "Vandal" in the edit summary. This allows sysops to quickly see editors that need to be blocked for vandalism without having to check each reverted edit. Help out the sysops by communicating with them in the rc log.
If all users with patroller rights could endorse in the comments section below: