Windows Defender

What Does Windows Defender Mean?

Windows Defender, now Microsoft Defender Antivirus, is a software application that safeguards systems from malware. It is an anti-spyware program built to fight unauthorized access and protect Windows computers from unwanted software. It was introduced with the Windows Vista installation pack, and was made available for free as part of Microsoft Security Essentials.


Windows Defender was previously known as Microsoft AntiSpyware. It is now part of the Windows Security suite and is called Microsoft Defender Antivirus, as we explain in our Microsoft Defender Antivirus review.

Techopedia Explains Windows Defender

Released in 2006, Windows Defender was a built-in anti-spyware application included with Windows Vista and Windows 7, and was later updated to include support for Windows XP and Windows Server 2003. Windows Defender was later incorporated into Microsoft Security Essentials, which targets a wider range of malware and is available as a free download.

Windows Defender was updated with the release of Windows 8. In Windows 8, rather than focusing solely on spyware, Windows Defender offered virus protection, like Microsoft Security Essentials.

Consumers are encouraged to consider third-party products that offer additional features to provide multi-layered security protection.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.