The antivirus program that comes with Windows. Previously called "Windows Defender" starting with Windows 8, it was retroactively added to Windows 7. Microsoft Defender scans files downloaded from any Windows Web browser.
Win Defender--> MSE--> Win Defender--> MS Defender
Windows Defender was originally an antispyware program acquired by Microsoft from GIANT Company Software in 2004. Defender was replaced by Microsoft Security Essentials (MSE) in 2009, which included antivirus scanning. In 2012, the Defender name was resurrected for the antivirus program built into Windows 8, which uses the same virus signatures as MSE. In a subsequent Windows 10 release, the name was changed from Windows Defender to Microsoft Defender. See
Microsoft Security Essentials.