Bing found the following results
Active Directory Domain Services Overview | Microsoft Learn
Active Directory - Wikipedia
What is Active Directory? A Beginner’s Guide
Active Directory 101: A Step-by-Step Tutorial for Beginners
Introduction to AD DS - Training | Microsoft Learn
Active Directory Domain Services - Training | Microsoft Learn
AD Step-by-Step Tutorial: Learn the Basics of Configuring AD - Comparitech
What is Active Directory: The Ultimate Guide | Petri
What is Active Directory? How does it work? | Quest
What is Active Directory (AD)? - TechTarget