Photon detection is a research area focused on the development and improvement of detectors capable of accurately and efficiently detecting individual photons. Photons are fundamental particles of light, and detecting them at the single-photon level is crucial for a wide range of applications in fields such as quantum information processing, telecommunications, medical imaging, and astronomy. Researchers in photon detection work on developing sensitive and reliable detectors that can detect and measure the properties of individual photons, such as their energy, polarization, and arrival time. Common types of photon detectors include photomultiplier tubes, avalanche photodiodes, and single-photon avalanche diodes. Advancements in photon detection technology have enabled breakthroughs in various scientific and technological fields, including the development of quantum computers, secure quantum communication networks, high-resolution medical imaging devices, and sensitive astronomical instruments.