This chapter examines the core components and functions of remote sensing systems, focusing on sensors and satellite platforms essential for Earth observation. It begins by exploring sensors, which measure electromagnetic radiation from the Earth’s surface in various forms such as optical, thermal, and microwave—each tailored to specific wavelengths of the electromagnetic spectrum. The chapter discusses the advantages, resolution capabilities, and limitations of different sensor types and scanning systems. It also covers the satellite platforms that carry these sensors, including Sun-synchronous and geostationary satellites, detailing their orbits, velocities, coverage areas, and applications. The history of key satellite programmes, the Indian Remote Sensing System, and its institutions is reviewed. The chapter also highlights recent advancements, including new sensor technologies like synthetic aperture radar and hyperspectral sensors for data processing and analysis. The chapter highlights the recent advancements in sensor and satellite technology and potential future advances. This chapter explores these topics to give readers a solid understanding of the fundamental principles enabling remote sensing data collection from space.