Azure Active Directory (Azure AD) is a cloud-based identity and access management service provided by Microsoft. It helps organizations manage user identities and control access to resources, applications, and services. Azure AD allows users to sign in and access multiple applications with a single set of credentials, enhancing security and user experience. With Azure AD, businesses can implement features like multi-factor authentication, self-service password reset, and conditional access policies. It integrates seamlessly with other Microsoft services, such as Microsoft 365, and supports third-party applications, making it a versatile solution for managing user access in a secure environment.