In cybersecurity, a 'listener' refers to a program or component that remains active on a device or network, waiting to receive incoming connections or commands. Often used by hackers, listeners are typically hidden and enable unauthorized remote access or control over the compromised system. Attackers use listeners to execute commands, steal data, or maintain persistent access without the user's knowledge. While listeners can also serve legitimate purposes in network administration, in a malicious context they are a key part of cyberattacks such as backdoors and remote access trojans.