The Internet Control Message Protocol, or ICMP, is a network layer protocol used for error messages and operational information exchange in IP networks. It helps devices communicate issues like unreachable hosts or network congestion, allowing for better troubleshooting and network management. ICMP messages are typically generated by network devices, such as routers and hosts, to report problems or provide feedback about the status of network operations. Common uses of ICMP include the ping command, which tests connectivity between devices, and traceroute, which tracks the path data takes through a network.