Tenant

When many customers run on one platform, each is a tenant: their own workspace, users, data, and settings, kept separate at the database level so nobody can see across the wall. Multi-tenant software serves them all from one codebase while keeping each one private.

It is a foundational security and design decision, not a feature bolted on later. Done right, a tenant's data is scoped and gated on every read and write, so isolation holds even as the platform grows.