Azure Active Directory
Azure Active Directory (AD) is a cloud-based directory and identity management service that permits you to have authentication, Single Sign-On (SSO), and security on your SaaS applications (Office 365 uses Azure AD).
Azure Active Directory can also be integrated with an existing on-premise Windows Server Active Directory and this scenario permits you to have a single way of authentication between on-premises and cloud applications:
Azure AD is multi-tenanted and geo-distributed, so it guarantees high availability.
In a NAV architecture implementation, you could use and set up this service for certain business requirements, such as showing Power BI reports from Power BI.com, directly on Microsoft Dynamics NAV. NAV 2017 has a wizard to perform this task by navigating to Departments | Administration | Application Setup | General | Assisted Setup: