Translation is the interpreting of the meaning of a text and the subsequent production of an equivalent text, likewise called a "translation," that communicates the same message in another language. The text to be translated is called the "source text," and the language that it is to be translated into is called the "target language"; the final product is sometimes called the "target text."

Translation must take into account constraints that include context, the rules of grammar of the two languages, their writing conventions, and their idioms. A common misconception is that there exists a simple word-for-word correspondence between any two languages, and that translation is a straightforward mechanical process; such a word-for-word translation, however, cannot take into account context, grammar, conventions, and idioms.

Translation is fraught with the potential for "spilling over" of idioms and usages from one language into the other, since both languages coexist within the translator's mind. Such spilling-over easily produces linguistic hybrids such as "Franglais" (French-English), "Spanglish" (Spanish-English), "Poglish" (Polish-English) and "Portuñol" (Portuguese-Spanish).

On the other hand, inter-linguistic spillages have also served the useful purpose of importing calques and loanwords from a source language into a target language that had previously lacked a concept or a convenient expression for the concept. Translators and interpreters, professional as well as amateur, have thus played an important role in the evolution of languages and cultures.

The art of translation is as old as written literature. Parts of the Sumerian Epic of Gilgamesh, among the oldest known literary works, have been found in translations into several Asiatic languages of the second millennium BCE. The Epic of Gilgamesh may have been read, in their own languages, by early authors of the Bible and of the Iliad.

With the advent of computers, attempts have been made to computerize or otherwise automate the translation of natural-language texts (machine translation) or to use computers as an aid to translation (computer-assisted translation).

The term

Etymologically, "translation" is a "carrying across" or "bringing across." The Latin "translatio" derives from the perfect passive participle, "translatum," of "transferre" ("to transfer" — from "trans," "across" + "ferre," "to carry" or "to bring"). The modern Romance, Germanic and Slavic European languages have generally formed their own equivalent terms for this concept after the Latin model — after "transferre" or after the kindred "traducere" ("to bring across" or "to lead across").

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