Daguerreotype
Invented by Louis-Jacques-Mandé Daguerre and introduced worldwide in 1839, daguerreotype was almost completely superseded by 1860 with new, less expensive processes yielding more readily viewable images. In the late 20th century, there was a revival of daguerreotypy by a small number of photographers interested in making artistic use of early photographic processes.
Daguerreotype
The discovery and commercial availability of the halides: iodine, bromine and chlorine a few years earlier (iodine was discovered by Courtois in 1811, bromine by Löwig in 1825 and Balard in 1826 independently, and chlorine by Scheele in 1774) meant that silver photographic processes that rely on the reduction of silver iodide, silver bromide and silver chloride to metallic silver became feasible. The daguerreotype is one of these processes, but was not the first, as Niépce had experimented with paper silver chloride negatives while Wedgwood's experiments were with silver nitrate as were Schultze's stencils of letters. Hippolyte Bayard had been persuaded by Arago to wait before making his paper process public.