As a passive, effective, and renewable way of decreasing cooling energy requirements without power input, radiative cooling has attracted considerable attention in the field of energy-saving applications. Historically, radiative cooling was limited at nighttime because radiators with strong thermal radiation lack high reflectivity in the solar radiation band. With the recent technological advancements in radiators, such as the development of photonic radiators and metamaterials, the advantages of diurnal radiative cooling has been demonstrated. In this paper, the current state of the art in passive radiative cooling technology is reviewed and updated. First, the fundamental principles of radiative cooling, which comprise different mathematical and physical descriptions, are introduced. Then, the advanced materials and structures of various radiators, which are popular topics in radiative cooling, are presented. Furthermore, application developments in radiative cooling are also summarized and its prospects are preliminarily analyzed. This study provides a detailed introduction and analysis of radiative cooling technology, thereby serving as a key reference for promoting the development of radiative cooling utilization.