The daguerreotype  /dəˈɡɛrətaɪp/ (French: daguerréotype) was the first commercially successful photographic process. The image is a direct positive made in the camera on a silvered copper plate. The raw material for plates was called Sheffield plate, plating by fusion or cold-rolled cladding and was a standard hardware item produced by heating and rolling silver foil in contact with a copper support. The surface of a daguerreotype is like a mirror, with the image made directly on the silvered surface; it is very fragile and can be rubbed off with a finger, and the finished plate has to be angled so as to reflect some dark surface in order to view the image properly. Depending on the angle viewed, and the color of the surface reflected into it, the image can change from a positive to a negative.

The very first daguerreotypes used Chevalier lenses that were "slow", and the light sensitive material was silver iodide made by fuming the plate with iodine vapour. This meant that the exposure in the camera was too long to conveniently take portraits, and the first subjects taken were street scenes and architectural studies. When Petzval lenses were introduced, with lenses of a larger diameter and the plate was sensitized with iodine and bromine forming light sensitive crystals of silver iodide and silver bromide, the exposures were reduced so that portraits could be taken. Usually, it was arranged so that the sitters leant their elbows on a support, or else head rests that did not show in the picture were used to help the sitters sit motionless, and this led to most daguerreotype portraits having stiff, lifeless poses. There were exceptions with lively expressions full of character by photographers who saw the potential of the new medium, and these are represented in museum collections and are the most sought after by private collectors today.