The book "Tunable Fiber Laser Based on Fiber-Bragg-Grating-Arrays" by Tobias Tiess provides a comprehensive examination of the development and application of fiber-based lasers that are based on fiber-Bragg-grating arrays. It highlights the revolutionary properties of lasers, which have transformed numerous industries and research fields since their invention in the 1960s. In particular, a novel concept is presented that combines a fiber-integrated laser layout with programmable operating modes to achieve high spectral flexibility. This flexibility allows for precise adjustment of the emission wavelengths of the pulsed laser across wide bandwidths, which is significant for emerging application areas such as biophotonics and spectroscopy. The book is aimed at professionals and researchers involved in the development of innovative light sources and those looking to explore the possibilities of fiber-based laser technology.