This book includes of a compilation of valuable information contributed by distinct veterans from across the globe, elucidating the recent research trends in both short- and long-period fiber grating technology. It is primarily intended for researchers already engaged in this area, but it is also useful for anybody with a scientific background who is interested in an up-to-date analysis of the current growth in this domain. It will also prove to be useful for engineers and scientists who have become recently involved in this field. The aim of this book is to examine the present research in this area, displaying the current progresses in the field of fiber gratings.