More builds were released in 2005, with the last Beta 1 refresh released on November 21, 2005.
In Windows Vista, it is possible to close the window and have the program run in the system tray while a scan is running.
However, in Windows 7, this functionality was removed and the window must remain open while a scan is running.
In Windows Vista and Windows 7, Windows Defender was superseded by Microsoft Security Essentials, an antivirus product from Microsoft which provided protection against a wider range of malware.
Upon installation, Microsoft Security Essentials disabled and replaced Windows Defender. MSE itself does not run on Windows versions beyond 7.
Windows Defender is an anti-malware component of Microsoft Windows.
It was first released as a free antispyware program download for Windows XP, shipped with Windows Vista and Windows 7 and made into a full antivirus program replacing Microsoft Security Essentials as part of Windows 8 and later versions.
Protection against viruses was added in Windows 8; Windows Defender in Windows 8 resembles Microsoft Security Essentials (MSE) and uses the same virus definitions.
In Windows 10, Windows Defender settings are controlled by the Settings app, and the Settings button opens the Settings app.
Windows Defender (Beta 2) was released on February 13, 2006.
It featured the program's new name and a significant user interface redesign.
The core engine was rewritten in C , unlike the original GIANT-developed one, which was written in Visual Basic. Also, since beta 2, the program works as a Windows service, unlike earlier releases, which enables the application to protect the computer even when a user is not logged on.