In the Gettext field Internationalization (i18n) means the process by which mark the text strings that exist in the source code of a program so that later will be recognized for translation at the time the program has to present that text message to the users in their own language.

It is not uncommon within the source code that these strings are written in English or perhaps in the native language of the programmer. In either case, if then the author want to extend the program to users who do not speak those languages, he will have to "internationalize" the sources of the program. The task is the creation of a special file with the extracted strings and enables for a translator to work on them. These files have the suffix .po

Localization (l10n) means the process by which one translates these strings to a specific language and prepare a special file for that language to be queried by the program when this have to present the messages to the user. These files have the suffix .mo

Both processes and the lateral needs that arise from them are the focus of the Gettext package.

The coordination of this effort was a implicit need and for that the Free Translation Project was created.