ICMP (Internet Control Message Protocol) is a network layer protocol used to send error messages, diagnostics, and operational queries.

Elaboration:

• Does not carry application data but helps in network troubleshooting.
• Used by commands like ping and traceroute.
• Detects unreachable networks, timeouts, and congestion.

Example:

A ping command uses ICMP to check the availability of a host:

bashCopyEditping google.com