In recent years localization has become a popular concept in both translation practice and theory. It has developed a language of its own, which, however, still seems to be little known among translation scholars. What is more, being primarily an industry-based discourse, the terms related to localization are very fluid, which makes theorizing about it difficult. Therefore, the aim of this article is, first of all, to explain the basic terms of the metalanguage of localization, as they are used by both localization practitioners and scholars, and, secondly, to make this metalanguage more consistent by proposing some general definitions that cover the basic concepts in localization. This, in turn, should, on the one hand, facilitate scholar-to-practitioner communication and vice versa and, on the other, should result in concept standardization for training purposes. In the conclusions the present discussion of the metalanguage of localization is linked to a more general debate on metalanguage(s) in Translation Studies and it is proposed that in the future we might witness the emergence of a new discipline called Localization Studies.