Environments
Isolated instances of a Dynamics 365 tenant — typically a production environment plus one or more sandboxes for development and testing.
An environment is an isolated instance of a Dynamics 365 tenant, with its own database, users, configurations, and code. A typical setup has one production environment plus one or more sandbox environments for development, testing, training, and data refreshes. Business Central includes one production environment per tenant by default, with additional production and sandbox environments licensed as add-ons. Dynamics 365 CRM-side apps and Finance/SCM follow a similar model with their own environment SKUs. Best practice is to develop in a sandbox, test in a separate UAT sandbox, and promote releases to production through a controlled lifecycle.