A place within Backstage where you create, edit, test and publish your Pages.
The Development Environment is where Developers mainly work, they create Tastics here before pushing them to the Staging and Production Environments.
The Production Environment is where your live website and Pages sit. If you save any changes here, they will go live to your customers.
"When I'm doing any tests with my Page Layout, I use the Staging Environment, then I can easily push them to the Production Environment when I know they won't break my Pages that are already live."