Louis Jacques Daguerre and Joseph Nicéphore Niépce (who was Daguerre's partner, but died before their invention was completed) invented the first practical photographic method, which was named the daguerreotype, in 1836.
Daguerre coated a copper plate with silver, then treated it with iodine vapour to make it sensitive to light. The image was developed by mercury vapor and fixed with a strong solution of ordinary salt. William Fox Talbot perfected a different process, the calotype, in 1840. Bo