In Pictures: Microsoft products you may not know w...
GIANT Antispyware was once a competitor of Webroot in eradicating the new category of spyware software, which, unlike viruses, hid on your computer and looked for certain keystrokes, such as the login and password to your online bank account.
Microsoft purchased GIANT in 2004 and renamed it Microsoft AntiSpyware before renaming it Windows Defender one year later. It would eventually be superceded by Microsoft Security Essentials, which broadened the level of coverage and protection beyond just spyware.
In Pictures: Microsoft products you may not know were acquisitions