Firstly, foreign language teaching is part of applied linguistics and applied linguistics is part (or a branch) of linguistics. Secondly, and more importantly, knowledge of linguistics will not only help language teachers to better understand the nature of language, but also help them better understand how to teach language. Theoretical views of language explicitly or implicitly inform the approaches and methods adopted in language teaching. In fact, linguistics, as the science of language, should be of fundamental importance for teachers of language. Virtually all aspects of language teaching can have implications from linguistics. At the macro level, linguistic theories influence our general orientation in approaches to language teaching. For example, the structural linguistic theory views language as a system of structurally related elements for coding of meaning. Accordingly, the target of language teaching is to teach the elements of this system, which are generally defined in terms of phonological units, grammatical units, grammatical operations and lexical items. At the micro level, linguistic knowledge helps teachers to better explain the specific language items they teach.