ICMP is not normally used by end-users or to send messages. It's main use is in diagnostics and checking that the network is functioning correctly.
ICMP is just one communications protocol on the web. Others include:
- Transmission Control Protocol (TCP) tcp
- User Datagram Protocol (UDP) udp
- Hypertext Transfer Protocol (HTTP) http
- Post Office Protocol (POP3) pop3
- File Transfer Protocol (FTP) ftp
- Internet Message Access Protocol (IMAP) imap