This book offers a focused, practical guide to MDE, covering its architecture, evolution, and key features. While centered on MDE, it also addresses broader cybersecurity concepts relevant to DevOps, SREs, developers, system administrators, and newcomers entering the field. You will explore endpoint protection principles, the threat landscape, and frameworks like MITRE ATT&CK, along with deployment across Windows, macOS, and Linux. It covers EDR, SOC operations, data protection with Microsoft Purview, and incident response using Live Response. With rising threats powered by AI, deepfakes, and organized cybercrime, this guide prepares you to secure hybrid and cloud infrastructures using Microsoft Defender for Azure and Microsoft 365, backed by practical configurations, case studies, and a forward-looking view of endpoint security.