The majority of the updates that come through Windows Update are for Windows Defender, and for good reason. Windows Defender helps make your antimalware and other security protections stronger.

Recently, Microsoft delivered its latest Defender patches for Windows 11 ISOs. These definitions are released from time to time alongside the general security updates available during Patch Tuesday.

For most people using a supported and fully updated Windows 11 computer, yes: Microsoft Defender Antivirus and the other protections inside Windows Security are sufficient as the primary antivirus.