New organic compounds with interesting and improved electronic and photonic properties are being reported on a daily basis, with new light-triggered materials being designed for molecular and bioelectronic devices. The relatively new concept of molecular photonics embraces photochemistry and photophysics, dealing with light-induced changes in materials and their electronic states as well as the field of optics. This volume begins with a background and survey of current light-related research fields, moving on to the fundamentals of molecular photonics. Subsequent chapters deal with the characteristics of photochemical reaction and typical processes of photophysical chemistry, while the last two chapters focus on the study of materials-induced changes in light. The most important concepts are summarized in overview tables to promote active understanding of new topics.