Intrusion Detection System (IDS)

An Intrusion Detection System (IDS) monitors network traffic or system activity for signs of malicious activity or policy violations. When suspicious activity is detected, the IDS generates an alert so security personnel can investigate. An IDS watches and warns — it detects threats but doesn't automatically block them.

IDS systems use signature-based detection (matching known attack patterns) and anomaly-based detection (identifying unusual behavior) to identify potential threats. They're a critical component of network security monitoring.