An artificial language is a language the phonology, grammar, and/or vocabulary of which have been consciously devised or modified by an individual or group, instead of having evolved naturally. There are many possible reasons to construct a language: to ease human communication (see international auxiliary language and code); to bring fiction or an associated constructed world to life; for linguistic experimentation; for artistic creation; and for language games.

The expression "planned language" is sometimes used to mean international auxiliary languages and other languages designed for actual use in human communication. Some prefer it to the term "artificial" which may have pejorative connotations in some languages. Outside the Esperanto community, the term language planning means the prescriptions given to a natural language to standardize it; in this regard, even "natural languages" may be artificial in some respects. Prescriptive grammars, which date to ancient times for classical languages such as Latin, Sanskrit, and Chinese are rule-based codifications of natural languages, such codifications being a middle ground between naive natural selection and development of language and its explicit construction.
The ASCII Table, a scheme for encoding character strings.

Mathematics, Logics and computer science use artificial entities called formal languages (including programming languages and markup languages, and some that are more theoretical in nature). These often take the form of character strings, produced by a combination of formal grammar and semantics of arbitrary complexity.

A programming language is a formal language endowed with semantics that can be utilized to control the behavior of a machine, particularly a computer, to perform specific tasks. Programming languages are defined using syntactic and semantic rules, to determine structure and meaning respectively.

Programming languages are employed to facilitate communication about the task of organizing and manipulating information, and to express algorithms precisely. Some authors[who?] restrict the term "programming language" to those languages that can express all possible algorithms; sometimes the term "computer language" is applied to artificial languages that are more limited.[citation needed]