This functionality comes in handy when you have modified a page, but prefer the old version of the page. You can recover the older version of your page as follow:
1. Towards the top right of the page, choose to open the sub-menu items by selectingand click “Page History”:
2. On the page history, you will see multiple versions of the current page. If you click on the Version number (v.3 for example), you can view the page before later edits were made.
3. If you need to, you can choose a previous version to be the new/current version by selecting the "Restore this version" link under the Operations heading.