The daguerreotype, introduced by Louis Daguerre in 1839, was the first practical and commercially successful photographic process. It uses a polished silver-plated copper plate coated with light-sensitive silver iodide. When exposed in a camera, the latent image is developed using mercury vapour, which turns the exposed silver iodide into a visible gray-white image. The final image is made permanent by treating the plate with a solution of sodium chloride. Daguerreotypes are noted for their exquisite detail, sharpness, and historical significance as a pioneering method in photography.