Silver was traditionally used in photographic film.
Traditional photographic film relies on light-sensitive silver halide crystals, usually suspended in a gelatin emulsion. When light strikes the crystals, it creates a latent image by changing a tiny portion of the silver compound. Chemical development then converts the exposed crystals into metallic silver, forming the visible image.
This chemistry made silver especially useful: its compounds respond to light, and the resulting metallic silver produces strong contrast. Black-and-white film images are essentially patterns of finely divided silver. Color film also historically used silver halides during exposure and development, although the final color image is formed mainly by dyes after the silver is removed.
“Photographic film” is now often associated with nostalgia because digital cameras use electronic sensors instead. Modern photographic materials still exist, but the classic film process is much less common. Palladium and platinum have been used in alternative photographic printing, yet silver is the canonical answer for traditional film.