Environments are virtual locations to run a group of applications together. Many companies operate multiple environments like a Development, Testing and Production Environment as they are working on an application. Environments isolate applications and data from each other so that you can make changes to any given environment without impacting other environments. This is particularly important for the Production Environment, as applications that are ready for customers are publically available in a Production Environment. You don’t want to make changes in the Production Environment without testing them first. This is why a Development & Testing Environment exists to be able to safely test changes before they are released into Production.

What do we mean by this?
The places where you do different things—work, home, etc.