This chapter primarily focuses on scientific-technical texts, along with their categorization and translation, but also views them in the context of spoken discourse. It first discusses the subject fields and sub-domains of scientific and technical texts, paying attention to special language, terminology and usage register. It then discusses text classification and specifies the translation work order, presenting the role of the different people involved in scientific-technical translation (author, commissioner, project manager, translation service provider, editor, and end user). Lastly, it pays attention to English as the hegemonic language of science and to language and terminology planning.