How to use Microsoft Defender, the antivirus security program on Windows 10

Formerly known as Windows Defender, Microsoft Defender is an antivirus protection program that's included with Windows 10.
Which

Is Windows Defender good enough, or do you need third-party antivirus software?

Microsoft's own antivirus service comes pre-installed on Windows, but our expert antivirus tests prove there are better alternatives. Tom MorganSenior Content Producer/Writer With over a decade of ...