Book excerpt: Polymer optical fibers (POFs) have been regarded as a viable alternative to silica fibers in a variety of sensing applications. Fiber optic sensors offer key advantages over other sensing technologies, which include immunity to electromagnetic interference, compact, lightweight, multiplexing capability, and higher sensitivity. This book gives an overview of the polymer optical fiber Bragg grating (POFBG) technology over the last 20 years, covering aspects related to the fiber Bragg grating fabrication and also sensing applications. The book is split into five chapters, and it is written in such a way that can provide a comprehensive and simple route to new users, scientists and engineers working or wishing to work in the field of POFBGs: Describes the systems commonly employed for producing fiber Braggs gratings (FBGs) in silica fibers that can be used for the production of POFBGs; Explores different laser sources for the inscription of POFBGs; Explores the capability of using this technology at the visible and infrared region, in different fiber types (e.g., step-index, microstructured, unclad, highly birefringent) and in fibers composed of different polymer materials such as PMMA, doped PMMA, PS and ZEONEX; Reports the fabrication of different types of POF gratings, such as uniform, phase-shifted, tilted, chirped, and long-period gratings; Shows the opportunities of POFBGs for a variety of sensing applications. The insight to the use of POFBGs provides a vision for the opportunities of this fiber optic technology.