This book is dedicated to the theory and methodology of geographical data acquisition, providing comprehensive coverage ranging from the definition of geo-referencing systems, transformation between these systems to the acquisition of geographical data using different methods. Emphasis is placed on conceptual aspects, and the book is written in a semi-technical style to enhance its readability. After reading this book, readers should have a rather good understanding of the nature of spatial data, the accuracy of spatial data, and the theory behind various data acquisition methodologies. This volume is a text book for GIS students in disciplines such as geography, environmental science, urban and town planning, natural resource management, computing and geomatics (surveying and mapping). Furthermore it is an essential reading for both GIS scientists and practitioners who need some background information on the technical aspects of geographical data acquisition.