Book excerpt: Continuous-flow photochemistry is an expanding field within chemistry. It unites the mass transfer enhancement of flow chemistry with the high energy field density of microscale geometries. Moreover, it provides means to scale photochemical reactions efficiently.This book gives an overview of both technological and chemical aspects associated with photochemical processes in microreactors. It provides analysis, the first of its kind, of these new technologies developed within the field of photochemical processes, with a description and case studies of practical implementation. It specifically looks at:By providing a deeper understanding of underlying concepts, coupled with numerous examples, this book is an essential reference for chemistry students, researchers and professionals working on photochemistry, photoredox catalysis, flow chemistry, process chemistry and reactor engineering.