Diffraction is an optical phenomenon in which light waves bend or change direction when they pass near an edge, aperture, or obstacle. In photography, diffraction occurs most noticeably when light passes through a small lens aperture, causing slight spreading of the light rays.
While diffraction is a natural part of optics, it can affect image sharpness, especially at very small apertures (high f-numbers), producing a subtle softening effect across the image. Understanding diffraction is important for photographers who aim to balance depth of field with image clarity, ensuring that their chosen aperture provides both sharpness and the desired focus effect.