A botnet is a network of compromised computers or devices controlled by a single entity, usually used to execute malicious activities. Botnets can be employed for various purposes, including launching distributed denial-of-service (DDoS) attacks, distributing spam, and spreading malware. Attackers typically infect devices through vulnerabilities or phishing tactics, turning them into bots without the owner's knowledge. The scale of botnets can greatly amplify the impact of cyberattacks, posing significant challenges for cybersecurity measures.