A sandbox separates configuration work and testing from production. Sandbox types differ in capacity, data-copy behavior, and intended use. Developer types primarily support metadata work without a production business-data copy. Partial Copy and Full serve different data and testing needs. Check the current edition and entitlement before assuming a type is available.
Choose the smallest environment that can prove the change, with enough representative data and access controls to make the test meaningful. A refresh replaces the sandbox's copied state, so protect any work you need before refreshing. This local simulator stores sandbox snapshots in the browser and never provisions a Salesforce environment. The same decision discipline applies: name the purpose, define what should be copied, and keep production data handling deliberate.