A photographic process invented and marketed in 1839 by Louis-Jacques-Mandé Daguerre (1787- 1851). The first practical photographic system, a daguerreotype was a positive print made on a light-sensitized copper plate. By 1860 new, less expensive processes had almost completely replaced it. Pronunciation here. Web resource here. Videos here and here.
Daguerreotype of Louis Daguerre by Jean-Baptiste Sabatier-Blot. 1844.