Simple definition
A Microsoft Entra guest user is an external user represented in an organization’s tenant so they can access shared applications or resources.
Technical definition
With Microsoft Entra External ID / B2B collaboration, the guest normally authenticates with their own credentials. An invitation creates a user object in the resource tenant; after redemption, the guest can be added to groups or assigned to applications according to the permissions granted. Access remains controlled by policies in the tenant that owns the resource.
What is it used for?
Collaborate with partners, suppliers, or customers without creating and managing a conventional internal corporate account and password for each external person.
Practical example
An external consultant is invited to the tenant. They redeem the invitation using their work identity and are then granted access to an authorized application and group without becoming a normal internal employee account.
Common issues
- Invitation remains in Pending Acceptance state
- Guest redeems the invitation with the wrong account or identity provider
- Guest object exists but is not assigned to the required group or application
- Conditional Access or cross-tenant settings block access
Key takeaway: The guest object exists in your tenant, but authentication can still be performed by the guest’s external identity provider.