This document discusses internationalization and localization in Transferwise. Localization (L10n) is adapting a product to meet language and cultural requirements of a target market, while internationalization (I18n) is designing a product to facilitate localization without engineering changes. 30% of Transferwise customers prefer non-English languages, so localization increases new users and conversions. Language launch prioritization considers demand, growth, market size, and profitability. Transferwise initially used external translators but now uses an in-house multilingual customer support team and translation management tools.