Microsoft Power BI Complete Reference

Azure AD B2B collaboration

Azure AD business-to-business (B2B) collaboration enables organizations using the Azure AD to work securely with users from any organization. Invitations can be sent to external users, whether the user's organization uses Azure AD or not, and once accepted the guest user can leverage their own credentials to access resources, such as dashboards and reports contained in a Power BI app. Just like users within the organization, guest users can be added to security groups and these groups can be referenced in the Power BI service. 

Prior to the existence of Azure AD B2B, it was necessary to create identities within Azure AD for external guest users, or even develop an application with custom authentication.

A guest ...