In Windows, many applications have something called a "product ID number", a "GUID" or a "Unique ID number". This number may be the same through Internet Explorer, Windows Media Player - even the operating system itself. Since this number nevers changes, it would be the PERFECT way a malicious person or even an advertising company could track your habits. Maybe through a malicious website ActiveX control, or java applet. Well why not just delete it? In this case, you would have a constant ID of nothing - and given the small number of people that might also have that "null" value, it could still be used to track you. ID-Blaster Plus works by changing these ID numbers frequently, destroying tracking tactics using these numbers. ID-Blaster can run from the system tray, using up very little resources, and constantly protect you in the background.....(free).....