What is a Rootkit ???

This term describes a collection of programs used by a hacker to evade detection while trying to gain unauthorized access to a computer. The term originated in the Unix world, although it has since been applied to the techniques used by authors of Trojans that run under Microsoft® Windows® to conceal their actions. Rootkits have been used increasingly as a form of stealth to hide Trojan activity. When installed on the system, rootkits are not only invisible to users, but they are designed to escape detection of security software as well. The fact that many people log into their computers with administrator rights, rather than creating a separate account with restricted access, makes it easier for cybercriminals to install a rootkit.