The revisions tool keeps a record of each of the post and page saved drafts, periodic autosaves and published updates.
You can open the preview revisions screen by clicking on the date and time of the revision you would like to review.
The preview screen displays what changes were made in each revision–what was added, what was moved and what stayed the same. By simply dragging the revisions slider or using the next/previous button you can see what changes have been made to a post or a page.
The revisions page also includes a ‘compare any two revisions’ mode that allows you to compare any two versions of a post or page. If you find an older version of the post or page you would like to restore, simply click the ‘Restore This Revision’ or ‘Restore This Autosave’ button, and your post or page will restore to the previous version.