Microsoft bought Windows Defender. It used to be a paid antivirus. > Windows Defender was initially based on GIANT AntiSpyware, formerly developed by GIANT Com

Microsoft bought Windows Defender. It used to be a paid antivirus. > Windows Defender was initially based on GIANT AntiSpyware, formerly developed by GIANT Company Software, Inc. The company's acquisition was announced by Microsoft on December 16, 2004. https://en.wikipedia.org/wiki/Windows_Defender#History https://en.wikipedia.org/wiki/Windows_Defender#History I've been using it exclusively for a decade.