Over the last decade, GIS (geographical information systems) has established itself as a collaborative information processing system. The vast domain of information it can process is ever increasing and so is its popularity. Yet this interdisciplinary field is not available to the vast community of students and academicians as a subject of study. This book addresses the GIS user domain encompassing students, users and engineers. Important aspects of geographical information science (GISc), which is the basis of GIS, are explained. The book aims to capture the basics of GIS from the point of view of a student. The requirements of GIS have been explained keeping in mind the general user’s level of knowledge. The processing capability of GIS along with the mathematics and formulae involved in arriving at a solution are explained for students and cartographers. The work flow of the whole system, its output and applications are illustrated from an engineer’s point of view.