Windows Security, previously known as Windows Defender, is a built-in security tool in Windows 10 and 11 that provides comprehensive protection against viruses and malware without requiring additional software. Users can perform manual scans, including Quick, Full, and Custom scans, to identify and eliminate threats. To run a scan, users must open Windows Security, navigate to "Virus & threat protection," and select the desired scan option. Windows Security also includes features such as real-time protection, firewall and network protection, app and browser control, device security, and account protection. It is essential to keep Windows Security updated with the latest virus definitions for optimal protection. Users can also schedule automatic scans for regular checks.