This book provides a comprehensive review of chlorophyll fluorescence in plants, spanning fundamental principles to advanced applications. Bridging scales from the global ecosystem level to cellular and molecular processes, it explores how plants interact with light and regulate photosynthetic efficiency under dynamic environmental conditions. The chapters cover a wide range of topics, including the history and evolution of chlorophyll fluorescence research, its critical role in photosynthesis monitoring, and recent breakthroughs in proximal remote sensing technologies. The book also outlines time-resolved fluorescence techniques, light re-absorption and scattering models, and their relevance from satellite observations to intracellular dynamics. Edited and written by leading experts in plant physiology, biophysics, and environmental science, this volume highlights the practical applications of chlorophyll fluorescence in plant stress detection, crop monitoring, and ecosystem assessment. It is an essential reference for researchers working in plant biology, biochemistry, ecology, environmental science, agriculture, and remote sensing. With its interdisciplinary scope, the book equips scientists and practitioners with the tools to advance sustainable agriculture, climate resilience, and ecosystem management. Combining theoretical insights with applied methodologies, it serves as a critical resource for understanding the complex interplay between light, photosynthesis, and plant health.