A photon is a fundamental particle of light, representing the smallest discrete unit of radiant energy that can be transmitted between two systems. Photons exhibit both wave-like and particle-like properties, forming the basis of electromagnetic radiation, including visible light.
In photography, understanding photons is essential for grasping how light interacts with sensors, film, and optical systems. The quantity and energy of photons striking a photosensitive surface determine exposure, brightness, and colour capture, making this concept central to both the science and art of image-making.