Sandbox
A sandbox is a development environment that the development team works in before code is ready to be deployed. Like the name suggests, it's a safe place to play around in—you can't interrupt anyone else's work in your sandbox, which makes it a great place to test out and prototype code ideas before sending them out to the world. One thing that makes sandboxes special is that there is usually only one person working in a sandbox at a time, and you can upload your changes to the sandbox directly at any time, which makes development much faster. This is in contrast to production environments, which always require a deploy to make changes as a safeguard.
The most important thing to know about a sandbox is that content can only go into a sandbox—it can't be cloned or exported out. Never do any content work in a sandbox. All content work must be in staging. This is because if you could take things out of the sandbox and go to one of our production environments, it would no longer be a safe place to experiment with code and develop it. If this were possible, there would be a risk of the work in a sandbox jeopardizing the production environment, including live and staging sites. Because these sites are absolutely critical, we do not want to take any chances with them, so there is no way to send information from sandboxes and other development environments to production. You can clone a site from production to a development environment, though. This allows you to test changes to the most recent content in a safe place.
All team members should keep this in mind as they are working on web projects. If you see someone doing any sort of content work on a sandbox, make sure they know that they will have to manually copy and paste everything they do into a staging site in order to launch that content.