Fiber lasers are key components that have attracted wide attention owing to their advantages such as compact structure, high peak power, high efficiency, and excellent beam quality. To date, considerable efforts have been undertaken to improve the emission performance of optical fiber lasers, including their pulse duration, peak power, and stability. Furthermore, high-peak-power fiber lasers have been adopted as an edge tool in both research and industry fields, such as nonlinear optics, optical imaging, laser processing, and 3D printing. The aim of this reprint is to provide a comprehensive exploration of fiber lasers and their diverse applications.