A method of photographic printing where the paper is sensitized by first coating it with sodium chloride, then coating again with silver nitrate. Subsequently the silver nitrate and sodium chloride combine to form silver chloride in the paper. Silver chloride is special because when struck by photons it has a tendancy to turn into metalic silver.
So the photographic process for salted paper then is to expose the paper through a negative and then to remove the remaining silver chloride from the paper with sodium thiosulfate.