What is a Rootkit? - Security Term

A rootkit is a type of computer program that hides its presence from the administrator of the machine. Usually installed as malware, rootkits are very difficult to detect and remove because they erase all evidence of their presence. Often, the only visible symptoms of a rootkit may be an unexplainably busy CPU or unusual network traffic. With today's high-speed CPU's and high bandwidth network connections, rootkits are almost impossible to identify. Typically, rootkits are used to cloak keyloggers and other spyware, distribute spam, or to provide privileged access to an unauthorised entity. The term is named for the Unix privileged user account, root, although today rootkits are available for most major operating systems including Linux, Mac OS-X, and Microsoft Windows.