A sandbox is a safe place to build a castle. If it gets knocked down, no big deal. It says that we use our computers for fun. I like that. A sandbox is any computer structure you're willing to build and then lose.
Cookies are a kind of a sandbox.
And cookies are just like the Preferences folder on a Macintosh. You can always drag it to the trash and start over. We'll build a firewall between a sandbox and your personal, safe world. A way to run scripts against the sandbox that synchronize between it and your private more protected world. In this one place, only a user request to synchronize, a request that can't be imitated by software, is required to start the process.