Botnet
A network of infected computers controlled remotely by an attacker, often used to send spam or launch large-scale attacks.
A botnet↗ is a network of computers or other internet-connected devices that have been infected with malware↗ and are secretly controlled remotely by an attacker, usually without their owners ever realizing it. Individual infected devices are sometimes called "zombies," and a botnet can range from a few hundred to millions of devices worldwide.
Attackers use botnets to carry out large-scale attacks that would be impossible from a single machine, most commonly sending spam↗, launching Distributed Denial-of-Service (DDoS) attacks, or mining cryptocurrency using the victim's stolen processing power. Keeping devices patched, using reputable security software, and being cautious about what you install are the main defenses against a device being recruited into a botnet in the first place.