Single-photon avalanche diodes (SPADs) are advanced photodetectors capable of detecting light under extremely low-light conditions, even single photons. Their compact size, high sensitivity, ease of integration, and strong resistance to electromagnetic interference have led to their widespread use in fields such as light detection and ranging (LiDAR), fluorescence lifetime imaging, spectroscopy, and quantum communication. These applications leverage SPADs for their precision, reliability, and ability to operate in challenging environments. This paper provides a detailed overview of SPAD, including its historical development, working principles, and device structure design. It further delves into the critical parameters and underlying principles that influence the performance of SPADs during design and manufacturing, particularly with respect to photoelectric detection applications. Key parameters such as dark count rate, photon detection efficiency, and time jitter are discussed in detail. Finally, the paper focuses on the design of quenching circuits, which are essential for controlling the avalanche process in SPADs, thereby ensuring stable operation and enhancing device performance.