Photography is the art and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science and business, as well as its more direct uses for art and video production, recreational purposes and mass communication. A lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, electronically processed and stored in a digital image file for subsequent display or processing; the result with photographic emulsion is an invisible latent image, chemically "developed" into a visible image, either negative or positive depending on the purpose of the photographic material and the method of processing. A negative image on film is traditionally used to photographically create a positive image on a paper base, known as a print, either by using an enlarger or by contact printing.
The word "photography" was created from the Greek roots φωτός, genitive of φῶς, "light" and γραφή "representation by means of lines" or "drawing", together meaning "drawing with light". Several people may have coined the same new term from these roots independently. Hercules Florence, a French painter and inventor living in Campinas, used the French form of the word, photographie, in private notes which a Brazilian historian believes were written in 1834; this claim is reported but has never been independently confirmed as beyond reasonable doubt. The German newspaper Vossische Zeitung of 25 February 1839 contained an article entitled Photographie, discussing several priority claims – Henry Fox Talbot's – regarding Daguerre's claim of invention; the article is the earliest known occurrence of the word in public print. It was signed "J. M.", believed to have been Berlin astronomer Johann von Maedler. The inventors Nicéphore Niépce, Henry Fox Talbot and Louis Daguerre seem not to have known or used the word "photography", but referred to their processes as "Heliography", "Photogenic Drawing"/"Talbotype"/"Calotype" and "Daguerreotype".
Photography is the result of combining several technical discoveries, relating to seeing an image and capturing the image. The discovery of the camera obscura that provides an image of a scene dates back to ancient China. Greek mathematicians Aristotle and Euclid independently described a pinhole camera in the 5th and 4th centuries BCE. In the 6th century CE, Byzantine mathematician Anthemius of Tralles used a type of camera obscura in his experiments; the Arab physicist Ibn al-Haytham invented a camera obscura and pinhole camera. Leonardo da Vinci mentions natural camera obscura that are formed by dark caves on the edge of a sunlit valley. A hole in the cave wall will act as a pinhole camera and project a laterally reversed, upside down image on a piece of paper. Renaissance painters used the camera obscura which, in fact, gives the optical rendering in color that dominates Western Art, it is a box with a hole in it which allows light to go through and create an image onto the piece of paper.
The birth of photography was concerned with inventing means to capture and keep the image produced by the camera obscura. Albertus Magnus discovered silver nitrate, Georg Fabricius discovered silver chloride, the techniques described in Ibn al-Haytham's Book of Optics are capable of producing primitive photographs using medieval materials. Daniele Barbaro described a diaphragm in 1566. Wilhelm Homberg described how light darkened some chemicals in 1694; the fiction book Giphantie, published in 1760, by French author Tiphaigne de la Roche, described what can be interpreted as photography. Around the year 1800, British inventor Thomas Wedgwood made the first known attempt to capture the image in a camera obscura by means of a light-sensitive substance, he used paper or white leather treated with silver nitrate. Although he succeeded in capturing the shadows of objects placed on the surface in direct sunlight, made shadow copies of paintings on glass, it was reported in 1802 that "the images formed by means of a camera obscura have been found too faint to produce, in any moderate time, an effect upon the nitrate of silver."
The shadow images darkened all over. The first permanent photoetching was an image produced in 1822 by the French inventor Nicéphore Niépce, but it was destroyed in a attempt to make prints from it. Niépce was successful again in 1825. In 1826 or 1827, he made the View from the Window at Le Gras, the earliest surviving photograph from nature; because Niépce's camera photographs required an long exposure, he sought to improve his bitumen process or replace it with one, more practical. In partnership with Louis Daguerre, he worked out post-exposure processing methods that produced visually superior results and replaced the bitumen with a more light-sensitive resin, but hours of exposure in the camera were still required. With an eye to eventual commercial exploitation, the partners opted for total secrecy. Niépce died in 1833 and Daguerre redirected the experiments toward the light-sensitive silver halides, which Niépce had abandoned many years earlier because of his inability to make the images he captured with them light-fast and permanent.