This chapter provides a context for the topics discussed in the rest of the book, by explaining our approach to the study of language, and positioning this approach in relation to other ways of thinking about language. Firstly, the chapter considers why language is a phenomenon worthy of study; we use an example of a letter to a newspaper to consider the ways in which language, society and power might be related. Secondly, the chapter considers the nature of language, and how its forms (i.e. its manifestations as spoken or written words, or as signs in sign language) and functions (i.e. what people use language for) may be described and categorised. Thirdly, the chapter explores some of the variations found in language systems, and the social meanings which are attributed to different languages, dialects and accents. Fourthly, the concept of power is introduced, with a discussion of some of the ways language creates and maintains power. The chapter concludes with a discussion of the term 'political correctness'.