Office 365 with Microsoft Azure AD is an enterprise-level cloud-based identity and access management solution.

You can continue reading Office 365 Multi-factor Authentication with Microsoft Azure Active Directory at https://blogs.msdn.microsoft.com/microsoft_press/2015/03/23/from-the-mvps-office-365-multi-factor-authentication-with-microsoft-azure-active-directory/.

What is Azure Multi-Factor Authentication? at https://docs.microsoft.com/en-us/azure/multi-factor-authentication/multi-factor-authentication.