Trigraph

A trigraph (from the Greek words tria = three and grapho = write) is a group of three symbols, most commonly letters.

Trigraphs are used in several fields, and for several purposes. Among them are:

In computing:
- A C trigraph, a character representation in the C family of programming languages.
- As octal or decimal representation of byte values.
- Mnemonics for machine language instructions.
- There are text matching and data compression algorithms which act directly on trigraphs.
In language:
- As language codes in ISO 639.
- A Trigraph (orthography), a sound representation in orthography.
- As abbreviations.
In cryptography:
- As substitution group in a substitution cipher.
As combinations in the Ling Qi Jing.

Trigraph is also the name of several businesses.