This book is entirely devoted to research in the area of ionic liquids, which are salts with melting points below 100 C. It explores the promise of ionic liquids and sets the research agenda for the field. With a distinct bias towards actual industrial R&D applications, the book is virtually a manifesto for the new age of Green Chemistry. The major industrial challenges to sustainability - the book's leitmotiv - are: reducing water use; increasing energy efficiency; reducing reliance of fossil fuel feedstocks; increasing use of renewables; including sustainability as a major economic criterion. Thereafter, the book goes on to consider precisely where ionic liquids can help in achieving this new vision, via new techniques, new processes, new reactions. The Safety/Health/Environment properties of the ionic liquids are also considered. Finally, it is clear that there needs to be a major increase in the number of workers studying ionic liquids if this promise of a new Green Chemistry is to be achieved.