How to Use Windows Defender to Protect Your Computer

Windows Defender (also called Windows Security or Microsoft Defender) is free antivirus and security software that comes built into every Windows 10 and Windows 11 computer. It runs in the background, protecting you from viruses, malware, spyware, and other threats — and for most people, it provides all the protection you need without purchasing additional antivirus software.

To open Windows Defender, click the Start button and type "Windows Security" in the search bar, then click on the Windows Security app. The main dashboard shows you an overview of your security status. Green check marks mean everything is good. Yellow or red indicators mean something needs your attention.

The most important section is "Virus & threat protection." Click on it to see when your last scan was performed and whether any threats were found. Under "Current threats," you will see if anything suspicious has been detected. Windows Defender runs a quick scan automatically, but you can run a manual scan anytime by clicking "Quick scan." A quick scan checks the most common places where threats hide and takes about 5 to 10 minutes.

For a more thorough check, click "Scan options" and select "Full scan." A full scan checks every file and program on your computer and can take an hour or more depending on how many files you have. Run a full scan if your computer is behaving strangely, if you recently downloaded something suspicious, or as a monthly maintenance step.

Under "Virus & threat protection settings," click "Manage settings" to see your protection options. Make sure "Real-time protection" is turned on — this continuously monitors your computer and blocks threats as they appear. Also ensure "Cloud-delivered protection" and "Automatic sample submission" are turned on for the best detection rates.

The "Firewall & network protection" section controls your Windows Firewall, which monitors internet traffic and blocks unauthorized connections. Make sure the firewall is turned on for all network types (Domain, Private, and Public). Do not turn off the firewall unless specifically instructed to do so by a trusted tech support professional.

Windows Defender updates its virus definitions automatically through Windows Update. You do not need to manually update it, but you can click "Check for updates" in the Virus & threat protection page to ensure you have the latest definitions.