What Is Microsoft Entra ID?
Compare Entra ID with traditional Active Directory, understand tenants and subscriptions, and learn how cloud identity differs from on-premises identity.
Introduction to Microsoft Entra ID
Microsoft Entra ID (formerly Azure Active Directory) is Microsoft's cloud-based identity and access management service. It is the identity backbone of Azure and Microsoft 365, handling authentication and authorisation for millions of users and applications worldwide. Every Azure subscription is associated with one Entra ID tenant that stores user identities and manages access to resources.
Entra ID vs Traditional Active Directory
Traditional on-premises Active Directory Domain Services (AD DS) manages identities using Kerberos and LDAP protocols, suited for domain-joined Windows machines in a corporate network. Entra ID is cloud-native and uses modern protocols — OAuth 2.0, OpenID Connect, and SAML — to authenticate users to web apps, SaaS services, and APIs from any device, anywhere. The two can coexist via Microsoft Entra Connect, which synchronises on-premises identities to the cloud.