More than anything else, this book is a tribute to Edsger W. Dijkstra, on the occasion of his sixtieth birthday, by just a few of those fortunate enough to be influenced by him and his work and to be called his friend or relation, his master, colleague, or pupil. This book contains fifty-four technical contributions in different areas of endeavor, although many of them deal with an area of particular concern to Dijkstra: programming. Each contribution is relatively short and could be digested in one sitting. Together, they form a nice cross section of the discipline of programming at the beginning of the nineties. While many know of Dijkstra's technical contributions, they may not be aware of his ultimate goal, the mastery of complexity in mathematics and computing science. He has forcefully argued that beauty and elegance are essential to this mastery. The title of this book, chosen to reflect his ultimate goal, comes from a sentence in an article of his on some beautiful arguments using mathematical induction:"... when werecognize the battle against chaos, mess, and unmasteredcomplexity as one of computing sci-ence's major callings,we must admit that 'Beauty Is Our Business'."