A Network Intrusion Detection System (NIDS) is a security tool designed to monitor network traffic for suspicious activities and potential threats. It analyzes data packets traveling across the network and identifies patterns that may indicate unauthorized access or attacks. By detecting these anomalies, NIDS helps organizations respond quickly to potential security breaches. NIDS can operate in two main modes: signature-based detection, which looks for known threats, and anomaly-based detection, which identifies unusual behavior. This dual approach enhances the system's ability to protect networks from a wide range of cyber threats, ensuring the integrity and confidentiality of sensitive information.