Answer Description
The Internet Control Message Protocol (ICMP) is used to control IP networks. It is used for error reporting, network congestion, and availability.
Wikipedia
The Internet Control Message Protocol (ICMP) is a supporting protocol in the Internet protocol suite. It is used by network devices, including routers, to send error messages and operational information indicating success or failure when communicating with another IP address, for example, an error is indicated when a requested service is not available or that a host or router could not be reached. ICMP differs from transport protocols such as TCP and UDP in that …
Internet Control Message Protocol - Wikipedia, the free encyclopedia