Formulated to react quickly when exposed to light, this paper contains silver halides in a gelatin binder. It is intended for handling in the controlled environment of a darkroom, printing with the aid of an enlarger, and requires chemical development to bring out the image in the print. Distinguished by their neutral, “black-and-white” tonality, gelatin silver papers first appeared in the 1880s, and became the most popular process of the 20th century thanks to their fast exposure times and relative ease of use.