Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. The English language draws a terminological distinction (which does not exist in every language) between translating (a written text) and interpreting (oral or signed communication between users of different languages); under this distinction, translation can begin only after the appearance of writing within a language community.

A translator always risks inadvertently introducing source-language words, grammar, or syntax into the target-language rendering. On the other hand, such "spill-overs" have sometimes imported useful source-language calques and loanwords that have enriched target languages.

Because of the laboriousness of the translation process, since the 1940s efforts have been made, with varying degrees of success, to automate translation or to mechanically aid the human translator. More recently, the rise of the Internet has fostered a world-wide market for translation services and has facilitated "language localisation".

The word for the concept of "translation", in English and some other European languages, stems from the Latin noun translatio, formed from the adverb trans, "across", and -latio, derived from latus, the past participle of the verb ferre, to "carry" or "bring". Thus, the Latin noun translatio and its cognate modern derivatives mean the "bringing across" (i.e., the transferring) of a text from one language to another.

In some other European languages, the word for the concept of "translation" stems from another Latin noun, trāductiō, derived from the verb trādūcō, "bring across", formed from the adverb trans, "across", and dūcō, to "lead" or "bring".

The Ancient Greek term for "translation" (metaphrasis, "a speaking across") has supplied English with "metaphrase" (word-for-word translation), as contrasted with "paraphrase" (rephrasing in other words, from paraphrasis). "Metaphrase" corresponds in one of the more recent terminologies to formal equivalence, and "paraphrase" to dynamic equivalence.

The concept of metaphrase (i.e., word-for-word translation) is an imperfect concept, because a given word in a given language often carries more than one meaning, and because a similar given meaning may often be represented in a given language by more than one word. Nevertheless, metaphrase and paraphrase may be useful as ideal concepts that mark the extremes in the spectrum of possible approaches to translation.

See also the entry for translation at Wiktionary.