i Preface Upon embarking on a book such as this, one may start with self- interest and ask What book would best serve me on my bookshelf? or perhaps What book would I have liked to have had when I began in this industry? One logically realizes that the same book could potentially be useful to numerous friends, colleagues, and co-workers throughout our industry, in addition to those who have recently joined the hair care field. Ideally, such a book would contain in-depth, detailed discussions on various important aspects of hair science. It would include the underlying fundamental science associated with this remarkable substrate, while recognizing that the ultimate reason for acquiring this knowledge usually relates to a desire to create products that will be sold to customers. Therefore, in addition to being a reference book, it should act as a guide for translating one’s understanding into practical applications. It should highlight topical issues and current trends within the industry. It should pay appropriate respect to the historical literature, while drawing attention to recent learning. Finally, it is desirable to be guided through these topics by individuals with significant knowledge and experience who are able to digest, condense, and critically assess the vast volumes of information available in many of these areas. These are the goals of this book. To address these goals we have been fortunate to assemble authors representing a broad cross-section of our industry including representatives from academia, consultancy, finished goods companies, and raw material suppliers. Therefore, this combination of authors can address topics from a range of perspectives. Despite diverse backgrounds, a commonality involves extensive, hands-on practical experience and significant expertise in their respective fields of interest. Indeed, most are frequent contributors to the