Internationalization (i18n)

Preparing code so it can support any language and region without changes: texts, dates, numbers, plurals and writing direction.

Texts live outside the code in message files, dates, numbers and currencies are formatted by the locale (in JavaScript with Intl), and plurals follow each language’s rules: Polish has different forms for 1, 2 and 5 files, so gluing a number to a word breaks. Layouts must survive longer words and right-to-left scripts. Internationalization is engineering work done once; localization then repeats per market.

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Related terms

Localization (l10n): Adapting a product to one market: translation, currency, formats, legal texts, images and tone.
Globalization (g11n): The whole effort of taking a product to many markets: internationalized code, localized content and the processes around them.
Numeronym (a11y, i18n, k8s): A word shortened to its first letter, the number of letters in between and its last letter, like a11y for accessibility.

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