Windows Defender is a free program that helps you stay productive by protecting your computer against pop-ups, slow performance and security threats caused by spyware and other potentially unwanted software. Windows Defender no longer supports Windows 2000 as mainstream support ended in June 2005. Windows Defender detects and removes known spyware from your computer, which helps make your Internet browsing safer.

The software uses automatic definition updates provided by Microsoft analysts to help detect and remove new threats as the threats are identified.