Drupal allows content administrators to save multiple versions of a page. Only one version is the current version displayed to site visitors. This is usually the most recent copy, but administrators can revert to an earlier version of a page that they have saved. This is useful if you need multiple versions of a page for different times of the year or if you are making major changes that need to be approved.
To create a new copy of a page, click on the 'Revision information' tab at the bottom of the edit form then check 'Create new revision'. To help remember what distinguishes this version from others, you can add a version description in the log message box. This description will appear in the revisions list.
To revert to a previous version of a page, click the 'Revisions' link/tab on the top right of the page next to 'View' and 'Edit'. (Only pages with revisions will have this link.)
The current version is displayed at the top. To roll back to an earlier version, click the 'revert' link next to the version to which you wish to revert.