How does Windows Genuine Advantage tool?

On the Microsoft Download Center or Windows Update Web site, the Windows Genuine Advantage Validation Tool, which is an ActiveX control, perform the validation check to verify that your copy of Windows is genuine. If your copy of Windows is genuine, you can continue to access the download.

ActiveX Controls are the building blocks that enable small Internet program works through a Web browser, like Internet Explorer. We use ActiveX controls to simplify you get the download essential software from Microsoft's website. ActiveX control that you requested to be downloaded and installed when you visit the Web site allows the WGA Validation Tool is run on the computer so it can verify the copy of Windows.

NOTE: The Windows Update Web site is only available to customers running genuine copies of Windows.