Guidance for Microsoft Defender for Endpoint (MDE) — enterprise endpoint security with EDR, next-gen antivirus, attack surface reduction, vulnerability management, and automated investigation. Covers onboarding, policy design, ASR rules, and EDR in block mode. WHEN: Defender for Endpoint, MDE onboarding, endpoint EDR, attack surface reduction rules, next-gen antivirus policy, device isolation, endpoint vulnerability management, EDR block mode, onboard devices to Defender.