This book is an interdisciplinary project that features an introduction to the basic principles of complexity theory and the application of these principles to the scientific study of language. At the core of this book are two words that fittingly encapsulate the main thread of the book's narrative, namely, interaction and emergence, which highlight the changing nature of language use and its relationship with human behaviors.

The twenty chapters in the book can be broadly classified into four sections. The first section covers chapters 1 to 3, which briefly introduce the basic concepts of complexity theory as they are originally used in the physical sciences, and how these concepts are brought to bear on linguistics. The second section includes chapters 4 to 11, which explains in detail how complexity theory is reflected at the micro levels of language study, such as phonetics, phonology, morphology, syntax, and discourse. These eight chapters follow progressively from one to the next, offering theoretical accounts of language while at the same time drawing on empirical evidence from real language use, such as data from the Linguistic Atlas Project and large corpora. The third section includes chapters 12 to 19, which relates the study of language to broader social and psychological phenomena, covering the macro-branches of linguistics such as cognitive linguistics, language acquisition, corpus linguistics, and historical linguistics. These chapters provide further evidence that the complex system of human speech is not only present in language per se, but permeates every aspect of the human experience. The fourth section comprises chapter 20, which stands alone as a summary of the entire text. This chapter first reviews the mechanical and reductionist approaches in modern science during the nineteenth century, and then highlights the advantages of complexity science as an alternative approach, which applies not only to the physical and natural sciences, but also to the humanities and social sciences.

Throughout this book, the authors present specific examples from both language and the natural world to illustrate the utility of complexity theory across the sciences, demonstrating that language, like other human behaviors, is also a complex system. At every step, a comparison is drawn between this new perspective on language study and traditional views of language, showing that complexity science is better positioned to fully characterize the complexity of language phenomena and thus represents the future of language study.

In summary, this introductory book is essential reading for undergraduate students who are new to the field of linguistics and those who wish to get a modern perspective on linguistics as a science. It will also prove valuable for language teachers who wish to demonstrate the relevance of linguistics to the real world.