What is a Salesforce Sandbox?
Although it is very easy and possible to make changes directly to configuration in Salesforce, it is a better idea to test out those changes in another environment which won’t affect your users. That’s why Salesforce includes a ‘sandbox’ for every production organisation where changes can be made and tested before moving them to production. This type of environment is called a sandbox. The number of sandboxes you can create and the types available depend on which edition you have, some come standard and some are available for an extra cost.
Each production organisation can have one or more sandboxes attached to it and they can be of different types. For example, most larger organisations will have at least 3 environments, a development environment, a test environment and a production environment. To cater for this, you would use sandboxes for the development and test environments. Changes can be developed in the development environment, tested in the test environment and when you are confident that the changes won’t break existing functionality, they can be moved into the production environment using changesets. It is also useful to use sandboxes to evaluate Apps from the AppExchange.