Internet Control Message Protocol (ICMP) is part of the IP suite as defined in RFC 792, Internet Control Message Protocol, for IPv4 and RFC 4443, Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification.
ICMP and ICMPv6 send and receive control and error messages used to manage the behavior of the TCP/IP stack. ICMP and ICMPv6 provide:
debugging tools and error reporting mechanisms to assist in troubleshooting an IP network
the ability to send and receive error and control messages to far-end IP entities