magician, google (or bing, or whichever) is your good, good friend. And sometimes Wikipedia is good enough. If you haven't already, read the introduction at Cloud storage - Wikipedia, the free encyclopedia
. That may be all you want to know.
Also, security has different meanings sometimes for different people. You may be talking about assurance that you will be able to restore your data if need be. If so, I wouldn't be concerned, but I would be aware that Protect doesn't do a full backup in the same sense as a full backup with Desktop Manager. I know you haven't asked, but my advice would be to do regular backups with desktop manager and rely on Protect for an emergency when you don't have access to your backup on your computer.