Azure Active Directory is a comprehensive, highly available identity and access management cloud solution.
Azure Active Directory comes in four editions—Free, Office 365 apps edition, Premium P1, and Premium P2.
Microsoft Azure Active Directory Premium combines core directory services, advanced identity governance, and application access management. Azure Active Directory also offers a rich, standards-based platform that enables developers to deliver access control to their applications, based on centralized policy and rules.
Offer a cloud-connected, seamless authentication experience with Azure AD Connect. Integrate your single or multi-forest Active Directory, as well as other on-premises directories, with Azure AD to use one identity to access any cloud or on-premises app.