The Third Edition of this book retains the basic principles of remote sensing, introduced in the earlier editions. It covers all aspects of the subject from electromagnetic radiation, its interaction with objects, various sensors, platforms, data processing, data product generation and end utilisation for earth resource monitoring and management. Apart from material that has retained value since the previous edition, this revised and updated edition presents additional information to keep the readers abreast of the emerging trends. The newer developments in sensor technology, supplementary information on image processing, data product generation, applications of remote sensing in disciplines such as archaeology, desertification and drought assessment are included. A relatively newer theme in remote sensing – GNSS remote sensing – has been introduced. Since remote sensing is used by professionals from varied disciplines, the book is designed to cater to readers from various backgrounds. For those intending to pursue graduate studies in remote sensing, this book serves as an overview and introduction, so that the basic concepts of all topics – science, technology and applications – of remote sensing are clear. This directs them to delve deeper into their specific field of interest. The book serves as a source of information for professionals who come across remote sensing in their work and would like to learn more about its principles and practical uses to support their professional/research activity. For faculty who want to widen their horizons, the comprehensive bibliography and relevant websites will be extremely helpful. Overall the book serves as a ‘single window’ source to comprehend the basics of the subject.