Photochemistry is the branch of chemistry concerned with the chemical effects of light. It is generally used to describe a chemical reaction caused by the absorption of ultraviolet radiation, visible light or infrared radiation. A molecule in its ground state can absorb light energy and go to a higher energy state. Photochemistry is of immense importance in nature as it is the basis of photosynthesis, vision and the formation of vitamin D with sunlight. Photophysics is a branch of science that deals with the physical properties of matter affected by light, and the physical effects of light. It mainly studies the processes that occur when sunlight, filtered through the Earth's atmosphere, interacts with matter present on the Earth. This book unfolds the innovative aspects of photochemistry and photophysics, which will be crucial for the progress of this field in the future. It presents researches and studies performed by experts across the globe. This book will prove to be immensely beneficial to students and researchers in this field.