Rootkits help intruders maintain access to a system without the user's knowledge.  These tools are used by malicious intruders to control, attack, or ferret information from systems on which the software has been installed.  Once installed by a virus or after a successful hack, rootkits run quietly in the background.  Rootkits can make themselves invisible to security systems, including antivirus tools and system-diagnostic tools such as Windows Task Manager. 

This page provides useful links to external websites that help you increase your understanding of Rootkits and what you can do about them.