In computing, internationalization and localization (American) or internationalisation and localisation (British English), often abbreviated i18n and L10n, are means of adapting computer software to different languages, regional peculiarities and technical requirements of a target locale.

Internationalization is the process of designing a software application so that it can be adapted to various languages and regions without engineering changes. Localization is the process of adapting internationalized software for a specific region or language by translating text and adding locale-specific components.

Localization (which is potentially performed multiple times, for different locales) uses the infrastructure or flexibility provided by internationalization (which is ideally performed only once before localization, or as an integral part of ongoing development).