This book is written for beginners in Computer Science. It is designed for persons who want to find out how to use a computer to solve a wide range of problems. Computer Science is the first term in this book you will want to understand. Traditionally, Computer Science has been regarded as a study of algorithms, which are step-by-step methods of solving problems. Algorithms themselves describe the data to use to solve a problem. In many ways, the focus of algorithms is the data needed to produce results. For this reason, Computer Science comes from two prominent Computer Scientists, E. Horowitz and S. Sahni. It is this second view of Computer Science that may help explain to you why so much space in this book is devoted to the data used by algorithms.