The silver gelatin process
Silver Gelatin photography methods were developed in the 19th century and became the standard way of producing black & white photographs for much of the 20th century. It has a rich tradition of journalistic as well as creative fine art photography that spans several decades. Well known mid century artists such as Edward Weston, Dorothea Lange, Ansel Adams, Imogen Cunningham, and countless others produced a lifetime's work using silver gelatin as their primary photographic process.
The term ‘silver gelatin’ refers to the coating on the photographic paper which consists of light sensitive silver halides suspended in a flexible gelatin emulsion. It is this coating that enables the paper to reveal an image when exposed to light, usually passed through a black & white negative, and then processed in chemistry consisting of a developer, stop bath and fixer. It's science and chemistry but it seems like magic.