A Sandbox is a copy of your production org used for development, testing, training, or staging. It's isolated — changes you make there never affect production until you deploy them. Every Salesforce org gets at least one sandbox; bigger editions get more.
There are four types, ordered by what they include:
- Developer Sandbox — metadata only, no production data. 200 MB storage. Refreshable once a day. Best for solo development.
- Developer Pro Sandbox — same as Developer but 1 GB of storage. Daily refresh. Useful when you need a bit more headroom for sample data.
- Partial Copy Sandbox — metadata plus a configurable subset of production data, defined by a Sandbox Template. 5 GB. Refreshable every 5 days. Used for UAT with realistic data.
- Full Sandbox — exact replica of production: all data, all metadata. Same storage limit as production. Refreshable every 29 days. Used for performance testing, full regression, and staging.
You access the sandbox at test.salesforce.com (or the org's My Domain test URL) and append .sandbox-name to your username. Refreshing a sandbox replaces it with a fresh production copy and discards any unmerged changes — common cause of lost work if not coordinated.