Windows Defender is an antivirus software component of Microsoft Windows. It was first released as a downloadable free anti-spyware program for Windows XP and was shipped with Windows Vista and Windows 7. It has evolved into a full antivirus program, replacing Microsoft Security Essentials in Windows 8 or later versions. Windows Defender Antivirus is available in Windows 10 and Windows 11, and in versions of Windows Server. It is a major component of next-generation protection in Microsoft Defender for Endpoint, which brings together machine learning, big-data analysis, in-depth threat resistance research, and the Microsoft cloud infrastructure to protect devices (or endpoints) in an organization.

Windows Defender provides real-time protection against malware, viruses, and security threats. It includes a number of real-time security agents that monitor several common areas of Windows for changes which might have been caused by spyware. It also has the ability to remove installed ActiveX software. Windows Defender’s App & Browser Control provides two different protections: reputation-based protection and exploit protection. Reputation-based protection is Windows Defender’s real-time protection. Windows utilizes a massive online database containing a list of millions of known apps and websites. Each of these apps and websites is assigned a reputation score, and if you try downloading a program or visiting a site with a low reputation score, Windows will block it.

Windows Defender is free and comes prepackaged with most Windows computers. If you subscribe to Microsoft 365 Personal or Family, you get access to the desktop and mobile app, Microsoft Defender for Individuals. Microsoft Defender Antivirus does a fine job of securing Windows 10 and 11 PCs that have no other protection. However, it doesnt beat the best competitors, including free ones, which do even better.