# ICMP

CEFR C2 · Noun

Source: https://englishreference.com/word/icmp
Updated: 2026-07-22

## Definition

Stands for Internet Control Message Protocol. A set of rules that computers use to send error messages and information about how the network is working.

For teachers: Abbreviation for Internet Control Message Protocol. A network layer protocol used by network devices to diagnose communication issues and send error reports, such as when a requested service is unavailable or a host cannot be reached.

## Examples

- The ping command uses ICMP to check if a server is online.
- Network administrators often monitor ICMP traffic to identify connectivity problems or potential security threats within the local network.
- While ICMP is essential for reporting delivery errors, many firewalls are configured to block certain types of these messages to prevent attackers from mapping the internal network structure.

## Usage notes

- Typically used as an uncountable noun or as a modifier in a noun phrase like 'ICMP packet' or 'ICMP request'.

---

From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.