After laying the foundation by explaining the fundamental principles of light propagation and optical resonators, this book delves into the realm of implementing resonators through a fiber-based approach. It extensively explores fiber-based resonators, encompassing a comprehensive discussion spanning from their intricacies of design to their pivotal roles in advancing quantum optics experiments. Furthermore, it details the design techniques, meticulously explaining the latest developments within this dynamic field. There are vivid illustrations highlighting the various applications of resonators in experimental optics and cavity quantum electrodynamics. Also, a discourse is presented regarding the future potential of fiber-based resonators in quantum technology. The book serves as a valuable resource for individuals with an interest in optical resonators and their boundless possibilities.