Internet Control Message Protocol (**ICMP**) is an internet protocol used by devices to tell each other about data transmission errors across the network. ICMP is used by a receiving device to *send a report to the sending device about the data transmission*. ICMP is commonly used as a quick way to troubleshoot network connectivity and latency by issuing the “ping” command on a Linux operating system. In the TCP/IP model, ICMP occurs at the [[Internet Layer]].