User blog comment:Wade Warren/How we deliver pages to you/@comment-3508190-20120302134443/@comment-3475413-20120302181741

Pecoes, you are correct. When you edit a page you get issued a session that bypasses the caching so you'll always have the most current version of the page to make sure your edits are visible.

If you use a different browser to view the page, it's possible that you will get an "older" version since the browser you are not editing with is "un-sessioned" and will use the version of the page that's in the cache.

When you publish your edit a purge command for that page is sent to the cache servers but for a myriad of reasons there can still be some delay before that purge command is received and executed by the caching servers. In those cases, an action=purge will purge the cache for the server you are currently connected to which will then force the page to be re-rendered with the most current version.