Example: "When he ran the antivirus software, he realized his computer had been part of a botnet."
A botnet is a network of computers that are controlled from a single source. While some botnets are used for legitimate cluster computing purposes, most botnets are created for malicious activity. Some examples include sending spam messages, spreading viruses, and attacking Internet servers.
Hackers create botnets by compromising the security of several computers and installing bots, or automated programs, on each system. This is often accomplished by exploiting a security hole in the operating system or a software program. Most users don't even realize their computers have been compromised since the botnet activity is typically hidden from the user. Therefore, it is smart to make sure your system firewall is turned on and to install antivirus software, which checks your computer for unusual activity on a regular basis.
Updated: May 31, 2010