In AV-Comparatives' July-October 2020 Real-World Protection Test, Microsoft performed decently with Defender stopping 99.5% of threats, ranking 12th out of 17 antivirus programs (achieving a robust 'advanced+' status).

How do I turn Windows Defender on?
To enable Windows Defender
Click the windows logo. ...
Scroll down and click Windows Security to open the application.
On the Windows Security screen, check if any antivirus program has been installed and running in your computer. ...
Click on Virus & threat protection as shown.
Next, select Virus & threat protection icon.
Turn on for Real-time protection.

Do I need additional antivirus if I have Windows Defender?
The short answer is that the bundled security solution from Microsoft is pretty good at most things. But the longer answer is that it could do better—and you can still do better with a third-party antivirus app.

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