Metaphor, defined as talking about one thing as if it was something else, where a similarity can be perceived between the two entities (Semino 2008) is an ordinary yet important part of everyday language. This chapter briefly traces a history of metaphor studies, from antiquity to the cognitive turn, and the most recent discourse-based approaches. It briefly touches on metaphor’s relationship with simile and metonymy, and outlines a well-established procedure for metaphor identification as an example of the kind of method that has to underpin any serious study of the trope. The chapter focuses on three key functions of metaphor in language: its role in semantic change, its role in language learning and education and its role as a tool of persuasion and framing, to highlight its relevance for English language studies and to demonstrate that it’s ‘necessary and not just nice’.