A sandbox is the type of environment that GCC should use to onboard new hires as well as develop, implement, and test new requirements. A sandbox is a copy of the production environment that allows the user to create and test changes without affecting the live data and users. A sandbox can have different types and sizes, depending on the purpose and scope of the changes. For example, a developer sandbox can be used to create and test code, a partial copy sandbox can be used to test large data sets, and a full sandbox can be used to perform performance testing and user acceptance testing. A production environment is the live environment that contains the real data and users. A production environment should not be used to onboard new hires or develop, implement, and test new requirements, because it could compromise the data quality and security, and disrupt the user experience. A Trailhead Playground is a type of environment that allows the user to learn and practice Salesforce skills using Trailhead. A Trailhead Playground is not connected to the production environment, and it does not have the same features and functionality as a sandbox.