How do I create a test environment in Salesforce?

Test environment in Salesforce is known by a term sandbox and based on requirement we can create a different type like full copy, partial copy, developer, developer pro, these all are the sandboxes that we can create and also they differ in storage. If you need to create a new sandbox, it must be initiated and created by an admin or a developer by going into your production environment and under setup go to sandbox and there you would find complete information (based on salesforce licenses) and then you may spin a new sandbox by following the on screen instructions.