There is the ability to look at previously saved versions of your content on each Page and Post. Revisions also allow you to compare changes between current and previous versions and revert to previous changes as well.
To access Revisions goto the Page or Post you want to edit. Look for Screen Options in the upper right corner.
Click the check box next to Revisions.
Click Screen Options again to close the screen options panel.
Then look for the Revisions panel below the Page or Post content and click a link to a version you wish to view.
In this page you can compare and revert to previous Revisions of each page or post.