The primary function of an intrusion detection system (IDS) is to monitor network traffic for suspicious activities and potential threats. IDS can be configured to detect various types of intrusions, such as unauthorized access attempts, malware infections, and abnormal traffic patterns. By analyzing data packets and network behavior, an IDS can generate alerts or take proactive measures to mitigate threats in real-time. This enhances an organization's security posture by providing insights into vulnerabilities and enabling quick responses to prevent data breaches or other cyber incidents.