Is used for supervisory messages at the internet protocol layer.

"ICMP" is used for supervisory messages at the internet protocol layer.
ICMP stands for Internet Control Message Protocol and it refers to a supporting protocol in the Internet protocol suite. It is utilized by network devices which includes routers and these are used to send error messages and operational data showing, for instance, that asked for service which isn't accessible or that a host or switch couldn't be come to.