Localization is everywhere in our digital world, from apps to websites or games. Our interconnected digital world functions in part thanks to invisible localization processes that allow global users to engage with all sorts of digital content and products. This textbook presents a comprehensive overview of the main theoretical, practical, and methodological issues related to localization, the technological, textual, communicative, and cognitive process by which interactive digital texts are prepared to be used in contexts other than those of production. Localization in Translation provides an interdisciplinary introduction to the main practical and theoretical issues involved in localizing software, web, video games, and apps. It discusses the many technological, cultural, linguistic, quality, economic, accessibility, and user-reception issues related to the different localization types. It also provides an updated overview of localization in an ever-changing technological landscape marked by advances in neural machine translation and AI. Each chapter includes a basic summary, key questions, a final section with discussion and assignments, as well as additional readings. Online resources with additional questions and assignments are included on the Routledge Translation Studies portal. This is the essential textbook for advanced undergraduates and graduates in translation studies and translation professionals engaged in localization practice.