OSSEC is an open-source security information and event management (SIEM) tool designed to monitor and analyze security events in real-time. It helps organizations detect unauthorized access, file integrity issues, and other security threats by collecting and correlating log data from various sources, including servers and network devices. The software operates on a client-server model, where agents installed on monitored systems send data to a central server for analysis. OSSEC supports various platforms, making it versatile for different environments, and it provides alerts and reports to help administrators respond to potential security incidents effectively.