Intrusion Detection Sensors (IDS) are devices or software applications that monitor network or system activities for malicious actions or policy violations. They analyze traffic patterns, detect suspicious behavior, and generate alerts when potential threats or unauthorized access attempts are identified. IDS can be network-based, monitoring entire network segments, or host-based, focusing on individual devices. By providing real-time detection and notification of security incidents, intrusion detection sensors help organizations respond quickly to cyber threats, minimize damage, and strengthen their overall security posture. They are a critical component in layered cybersecurity defense strategies.