A photograph or photo is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor, such as a CCD or CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene’s visible wavelengths of light into a reproduction of what the human eye would see. The process and practice of creating photographs is called photography. The word photograph comes from the Greek φῶς (phos), meaning “light”, and γραφή (graphê), meaning “drawing, writing”, together meaning “drawing with light”.
The first permanent photograph was made in 1826 by Joseph Nicéphore Niépce. This half-silvered plate covered with bitumen was exposed under an ordinary engraving and produced the earliest known clear and reasonably bright negative image[citation needed], but it could only be reproduced by copying it with a camera obscura. In 1829 Niépce entered into a partnership with Louis Daguerre and the two collaborated to work out a similar but more sensitive and otherwise improved process. After Niépce’s death in 1833, Daguerre concentrated on silver halide-based alternatives. He named this first practical process for making photographs with a camera the daguerreotype, after himself. Its existence was announced to the world on 7 January 1839 but working details were not made public until 19 August 1839. Other inventors soon made improvements which reduced exposure time from hours to minutes, making portrait photography truly practical and widely popular.
The daguerreotype had some inherent flaws that limited its popularity; most notably the fragility of the images produced which were easily damaged during processing or handling, as well as their one-of-a-kind nature precluding any copies being made without expensive duplicating equipment. Inventors set about working out improved processes that would be more practical; Frederick Scott Archer invented wet collodion positive glass plate negatives in 1850, leading to widespread adoption of his process which replaced earlier methods based on metal plates; American photographer Mathew Brady was instrumental in making photography widely practiced during the American Civil War by employing hundreds of cameramen (some armed only with hand held cameras) to document battle scenes and other events. Paper film was finally introduced commercially by George Eastman in 1889, followed by celluloid film, pioneered by Hannibal Goodwin and John Carbutt in 1889/90.:126 Celluloid brought several important advances: it was thinner than paper so did not need stiffening during manufacture; it could be coated prior to cutting into strips saving considerable post-processing effort; most importantly celluloid could be stripped from its backing paper support allowing roll film cameras able to take many sequential frames automatically while reloading with fresh film.:23–24:354–355 These advances rapidly drove Silver halide based photography underground where it became largely disused except for specialised applications such as medical X-rays because its principal competitor gelatin dry plates were significantly cheaper to produce per frame and required much less complicated darkroom processing procedures though they suffered from shorter shelf lives due largely to brittleness once exposed to high temperatures or humidity.:263 With further development led by companies like Kodak,:425 Rollfilm remained standard for amateur snapshot cameras throughout most of the 20th century until technological advancements such as automatic loading 35mm cassette films led to mass market adoption of smaller format cartridge films beginning in 1972 with 110 format followed closely thereafter by 135 (35mm).:537 In 2008 about 80% of still cameras used 135 film cartridges while over 90% of movie cameras used larger format magnetic tape stock leaving rollfilm all but extinct outside niche markets such as instant cameras where its economical manufacturing costs continue to give it an advantage over digital print media despite significant disadvantages regarding quality when compared against inkjet prints derived from scans of original negatives or slides.