What is "botnet"

n. (context Internet English) A collection of zombies that are controlled by the same cracker; a collection of compromised computers that is slowly built up then unleashed as a DDOS attack or used to send very large quantities of spam.

A botnet is a number of Internet-connected computers communicating with other similar machines in which components located on networked computers communicate and coordinate their actions by command and control (C&C) or by passing messages to one another (C&C might be built into the botnet as P2P). Botnets have been used many times to send spam email or participate in distributed denial-of-service attacks. The word botnet is a combination of the words robot and network. The term is usually used with a negative or malicious connotation.