The Purge this Page block is a system block designed to provide a targeted cache clear of one specific page where the you can see your updated content, but the visiting public cannot. 

How to add the Purge this Page block to your site

1. Navigate to Shortcuts » Blocks
2. Scroll down to the Footer Credits region
3. Click the Footer Credits' Place block button
4. In the "Filter by block name" field, type in Purge
5. From the filtered list, click the Place block button for the Purge this Page block
6. Under the Visibility » Roles section it is essential that you select the following user accounts in order to give proper access and avoid this block being visible to the public:
   1. Editor
   2. Site Manager
   3. Administrator
   4. Site Builder
      
7. Click the Save block button to finish.
8. The block, now visible only to logged in users, will display in the footer, titled "Purge this Page" with a Clear button option.