Support undo and redo.
In sequential processes like e-commerce transactions or long forms, let users to undo an error without undoing all their work . If the site uses frames or generates dynamic pages on the fly, this may not work. If this is the case, provide clearly marked links to return the user to the original state. While a user may accidentally choose an unwanted link or action, a site should never make unwanted demands on a user . For instance, many sites force a particular browser version or screen resolution on the user.