In contrast to literary or cultural studies linguistics is not taught in the EFL classroom, yet, it plays a major role in any English language teaching degree. Given this discrepancy it does not come as a surprise that students sometimes ask: "I want to be a teacher! Why do I need all this?" The main goal of this textbook is to demonstrate the relevance of linguistic expertise for the EFL classroom. It explores a wide range of topics (phonetics/phonology, lexis, corpus linguistics, text linguistics and the power of language) with a clear focus on providing a convincing answer to the question above. With its highly accessible style and layout, a wealth of examples and exercises as well as a large range of additional innovative online materials this textbook sets out to convince its readers that they will be better teachers if they are good linguists.