This chapter offers a general discussion of the phonetics and phonology of stop preaspiration, a central empirical concern of the book, in both synchronic and diachronic perspective. Preaspiration has a reputation as a cross-linguistically unusual feature, and I argue that this exoticization has hindered a more critical approach. Building on recent empirical work that has contributed to demystifying this phenomenon, the chapter lays the groundwork for the analysis of preaspiration in subsequent chapters. It presents the general approach to the phonetics and phonology of laryngeal contrast employed in the book; justifies the definition of preaspiration and analytical criteria used in subsequent analyses; and provides an explicit account of how preaspiration is expected to develop diachronically within the context of the life cycle. The chapter also offers critical discussion of the link between preaspiration and consonant quantity, a recurrent theme in the literature that is relevant to all the case studies considered later in the book. It concludes with a brief account of phenomena allied to preaspiration such as sonorant devoicing, and their import for the book’s argument.