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Microsoft Defender Antivirus 30

Sep 13, 2025

Overview

This lecture explains the features and operation of Microsoft Defender Antivirus within Windows, focusing on enabling, disabling, and updating virus and threat protection settings.

Microsoft Defender Antivirus Overview

  • Microsoft Defender Antivirus is integrated into Windows and enabled by default to protect against viruses and malware.
  • It is accessed through the Windows Security app, under the "Virus & threat protection" section.
  • The app may be called Defender Antivirus, Windows Defender, or Microsoft Defender Antivirus depending on Windows version.

Accessing Windows Security App

  • Use the Windows search function to find the Windows Security app by typing "security."
  • The app provides features like account protection, firewall, network protection, app/browser control, and virus/threat protection.

Managing Virus and Threat Protection

  • Virus & threat protection is the main section for antivirus settings.
  • Real-time protection scans files as they are transferred in and out of the system to detect malware.
  • It is recommended to leave real-time protection enabled unless troubleshooting requires it to be turned off.

Adjusting Antivirus Settings

  • Go to "Manage settings" under virus and threat protection to enable/disable real-time protection.
  • Additional options include cloud-delivered protection, automatic sample submission, tamper protection, controlled folder access, and exclusions.
  • Disabling real-time protection prompts a warning that the device is now vulnerable.

Updating Virus Definitions

  • Antivirus applications use signature definitions to identify malware; keeping them up-to-date is critical.
  • Definition updates are usually automatic, but can be checked manually in the threat and protection updates section.
  • The "Check for updates" option ensures you have the latest protection by downloading and installing new definitions.

Key Terms & Definitions

  • Real-time protection — Monitors and scans file activity in real time to detect malware.
  • Virus signature/definition — Database used by antivirus software to identify known malware.
  • Windows Security app — Central interface for managing security features on Windows.

Action Items / Next Steps

  • Practice navigating to the Windows Security app and adjusting real-time protection.
  • Manually check for antivirus definition updates on your device.
  • Review settings for cloud-protection, sample submission, and folder access as needed.