A translated text discussing concepts that are unknown in the country of its intended use will there remain incomprehensible. The translation has to be adapted in such a case. The translator can add comments in footnotes or brackets. A more elegant method would be to modify the text in a way that the concept gets understood. The translation is localized, which means, it is assigned to a certain country. When translating technical documents such methods are particularly important. An engineer using a translation for his work does not want to worry about strange habits in foreign countries. He needs a text written in the same way and using the same expressions as the documents he usually is confronted with.
When translating software manuals there is the problem that most application software is based on existing operating systems whose user interfaces have already been translated. In such a case the translator has to use the existing translations. As an example we consider the sentence: "the program returns the message: invalid number". The text of the message has to be translated exactly in the known way. If the translator puts in another text with the same meaning, for instance "not a valid number", the user does not obtain on his screen what is written in his manual. Adaptations of this type are difficult to make, as quite often the translator cannot easily find the manual of an operating system written in a language that is not spoken in the country where he resides.