Every day, approximately 89.5 billion unsolicited messages (i.e. spam) are
sent by computers that have been compromised and are part of a botnet.
Botnets - apart from inundating out inboxes with spam - can also be used for
ulterior purposes such as executing DDoS attacks or hosting websites, so
understanding the "modus operandi" and size behind the well-known names is a
good idea.