The main purpose of this book is to bring together much of the research conducted in recent years in a subject I find both fascinating and impor­ tant, namely fairness. Much of the reported research is still in the form of technical reports, theses and conference papers, and only a small part has already appeared in the formal scientific journal literature. Fairness is one of those concepts that can intuitively be explained very brieft.y, but bear a lot of consequences, both in theory and the practicality of programming languages. Scientists have traditionally been attracted to studying such concepts. However, a rigorous study of the concept needs