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Invented by Louis-Jacques-Mandé Daguerre and introduced worldwide in 1839, daguerreotype was almost completely superseded by 1860 with new, less expensive processes yielding more readily viewable images.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.
Calotype
In late 1840, Talbot worked out a very different "developing-out" process (a concept pioneered by the daguerreotype process introduced in 1839), in which only an extremely faint or completely invisible latent image had to be produced in the camera, which could be done in a minute or two if the subject was in bright sunlight. The paper, shielded from further exposure to daylight, was then removed from the camera and the latent image was chemically developed into a fully visible image. This major improvement was introduced to the public as the "calotype" or "talbotype" process in 1841.