This book has two related purposes. The first is to demonstrate the extent and importance of language play in human life; the second is to draw out the implications for applied linguistics and language teaching. Language play should not be thought of as a trivial or peripheral activity, but as central to human thought and culture, to learning, creativity, and intellectual enquiry. It fulfils a major function of language, underpinning the human capacity to adapt: as individuals, as societies, and as a species.