The word “botnet” is formed from the words “robot” and ”network.” Cyber criminals use special Trojan viruses to breach the security of several users’ computers, take control of each computer, and organize all the infected machines into a network of “bots” that the criminal can remotely manage.
Sources:
NIST SP 1800-15B
from
Kaspersky Cyber Security Resource Center
NIST SP 1800-15C
from
Kaspersky Cyber Security Resource Center