Active Directory (AD) is Microsoft's directory service that provides centralized identity and access management for Windows domain networks. It creates a hierarchical structure for organizing and securing network resources, including users, computers, groups, and applications across an organization's entire IT environment. Active Directory stores critical information about every entity on the network, enabling administrators to authenticate users, assign permissions, deploy software, and enforce security policies through mechanisms like Group Policy.

As a cornerstone of enterprise cybersecurity, Active Directory acts as the primary gatekeeper controlling access to sensitive data and critical systems. It uses industry-standard protocols like LDAP (Lightweight Directory Access Protocol) to integrate with complex enterprise architectures. Because AD centralizes authentication and authorization, its secure configuration and continuous monitoring are essential for maintaining strong defensive capabilities against cyber threats. A compromised Active Directory can give attackers widespread access to an organization's entire network infrastructure.