Restoring an Older Version of a Page

To restore an an older version of a page:

Go to the page, open the 'Tools' menu and select 'Page History'. The 'Page History' view will open, showing a list of all versions of the page, ordered from newest at the top to oldest at the bottom.
Click 'Restore this version' beside the desired version.
Change the default comment if desired and click 'OK' to restore the desired version.

All page history is retained. Restoring an older version creates a copy of that version. For example, in the screenshot below, if you selected v.39 and clicked 'Restore this version', a copy of v.39 would be created. This copy would be v.42 and would become the current version.
You can click a version number's link to view the contents of that page version.
Select the check boxes of two different versions and click 'Compare selected versions' to view the changes made between them.
If you are viewing a specific page version, you can restore that version of the page by clicking 'Restore this Version' on that page.
To get back to the page history view, click 'View Page History'.

Screenshot above: Restoring an Older Version of a Page