Glossary
Tenant
An isolated instance of Microsoft 365 belonging to a single organisation.
A tenant is the isolated instance of Microsoft 365 that belongs to a single organisation. It has its own Entra ID directory, its own users and groups, its own SharePoint and Exchange Online services, and its own settings — all separated logically from every other tenant. Each tenant has a primary .onmicrosoft.com domain (assigned at sign-up) and one or more custom domains (yourcompany.com) that you verify and bind to it. Tenant boundaries are strict: data, identities, and policies do not cross them by default. Cross-tenant access settings, B2B collaboration, and Multi-Tenant Organisations exist to bridge tenants when needed.