Translation & localization

You are making a product speak more than one language correctly — not word-for-word. The job splits in two, and confusing them is the root cause of "we translated everything but the dates are still American."

• i18n (internationalization) = engineering the code so it can hold any locale: no hardcoded strings, externalized catalogs, locale-aware formatting, locale routing. Done once.
• l10n (localization) = the per-locale content and cultural formatting: the actual translations, plural rules, date/number/currency conventions, RTL layout. Done per language, repeatedly.

Sequence matters: do i18n first. Teams that skip it end up retrofitting string extraction under a launch deadline, which is when concatenation and count === 1 bugs ship.

Route out fast