In regards to cybersecurity, what does the term 'botnet' refer to?

The term 'botnet' specifically refers to a group of devices that have been compromised and infected with malware, allowing them to be remotely controlled by a malicious actor. These devices, often including computers, servers, and Internet of Things (IoT) devices, can be used collectively to perform various harmful activities, such as launching distributed denial-of-service (DDoS) attacks, stealing personal information, or facilitating spam campaigns.

This definition aligns with the concept of a botnet being a network of 'robots' (or bots) that act in unison under the direction of the attacker. The other options describe unrelated concepts; ransomware is a type of malware that locks or encrypts data for ransom, securing data pertains to protective measures against unauthorized access, and social engineering involves manipulating individuals into divulging confidential information. Thus, the correct choice accurately captures the essence of what a botnet entails in the cybersecurity landscape.