The Atomx Sandbox is a copy of the real Atomx database that can be used to experiment with. Changes to the sandbox don't affect ad serving or the real database. Basically changes to the sandbox only affect the sandbox. This makes it possible to test all kinds of things on the Sandbox without worrying if it might go wrong or how it might affect things.
Quickstats and reporting data for the sandbox are exactly the same as the real data making the sandbox more flexible for testing.
The sandbox database is reset to the current state of the real database each Sunday at 23:00 UTC.
The Control Panel URL for the sandbox is: https://sandbox-cp.atomx.com/
Seeing as the sandbox is a copy of the real database the login you use for the real Atomx is also valid for the Sandbox.