Active Directory (AD) is a directory service developed by Microsoft for Windows domain networks. Coursera's Active Directory catalogue teaches you about managing access to resources, Windows Server administration, and the intricacies of AD architecture. You'll learn about the fundamentals of domain controllers, organizational units, group policy, DNS integration, and forest trusts. Additionally, you'll gain insights into user and group management, permissions, and security protocols. Master necessary skills like implementing Group Policy Objects (GPOs), managing user accounts, and troubleshooting Active Directory issues to strengthen your IT administration and network management capabilities.