For successful localisation, products must be technically and culturally neutral. Effective internationalisation reduces the time and resources required for localisation, improving time-to-market abroad and allowing simultaneous shipment. In orther words, internationalisation abstracts out local details, localisation specifies those details for a particular locale.
It also includes the separation of user interface text e.g. in dialog boxes and menus. All the text used by an application may be kept in a separate file or directory, so that it can be translated all at once. User interfaces may require more screen space for text in other languages.
The abbreviation i18n means "I - eighteen letters - N".