This chapter describes the role of remote sensing in determining the distribution and yield of crops. It discusses the physical basis for remote sensing and its historical development. The physical basis for remote sensing is the distinctive character of electromagnetic radiance from natural and man-made scenes. Remote sensing is the acquisition of information about the Earth's surface from measurements of radiated energy made by aircraft or spacecraft-borne sensors. It discusses the basic systems and concepts involved in the acquisition and analysis of remotely sensed data. The material will be presented in the form of an energy-flow profile, consisting of (1) the source of energy, (2) energy flow through the atmosphere, (3) its interaction with the target, (4) measurement and recording of energy flow, and (5) processing and analysis of recorded energy. The chapter discusses the potential agricultural applications of remote sensing, including (1) crop identification and area estimation, (2) crop condition assessment, (3) yield forecast and estimation, (4) rangeland surveys, and (5) soil mapping.