This book focuses on the applications of various types of fractional-order differential equations. The authors present their latest research results. This book for the first time  introduces  the concept of general fractional chaotic systems and their synchronisation,  investigates  the synchronisation of a fractional coupled reaction-diffusion system using a sliding mode control approach, and  considers  the impacts of fear and prey escape on a fractional-order prey-predator system with Beddington-DeAngelis functional response. Authors believe that these recent research results can promote the applications of fractional-order differential equations in diverse areas. The book will be attractive to researchers in various fields of mathematics, biomathematics and engineering. Graduate students in related fields may also find this book useful.