What it means
Windows Sandbox is an isolated Windows desktop built with virtualization on supported editions. Programs installed inside it are discarded when the sandbox closes. It can reduce changes to the host when testing a legitimate app, but network communication is available by default and a successful test says little about a program's intent.
A real-world example
You try a publisher's new document editor in Sandbox and it runs. This shows it works in that temporary environment. It does not establish that the publisher is honest or that the app will respect privacy when installed on your main PC.
What to do
Verify the download's origin independently, limit data transferred into the sandbox and close it after testing. Do not sign into important accounts or treat it as an invitation to analyze suspected malware without training and stricter controls.
The distinction that matters
A sandbox is not a browser private window and not a full backup. Microsoft's overview says its state disappears on close, while warning that default networking may expose internal networks.
Microsoft's Windows Sandbox overview
