This book explores the aggregation-induced emission (AIE) effect, which has opened new avenues for the development of advanced luminogenic materials in the aggregate or solid state. By enabling light emission in the practically useful solid state, AIE has the potential to significantly expand the technological applications of luminescent materials. This book addresses principles, methods, and applications of AIEs, offering a new platform for the investigation of light-emitting processes from luminogen aggregates. Applications of AIE include biomedical diagnostics, sensor materials, and optoelectronic devices, among others, and are described in detail within the book. The development of a new generation of AIEgens, a deep understanding of the AIE mechanism(s), and the exploration of advanced technological applications will enable this exciting field to develop further. Headed by the pioneering researcher who started the field, Professor Ben Zhong Tang, this book combines both principles and applications and brings together global researchers in the field to report the progress, current challenges, and potential breakthroughs that may be accomplished in the near future.