Found photography is a genre of photography and/or visual art based on the recovery (and possible exhibition) of lost, unclaimed, or discarded photographs. It is related to vernacular photography, but differs in the fact that the "presenter" or exhibitor of the photographs did not "shoot" the photograph itself, does not know anything about the photographer, and generally does not know anything about the subject(s) of the photographs. Found photos are generally acquired at flea markets, thrift and other secondhand stores, yard sales, estate and tage sales, in dumpsters and trash cans, between the pages of books, or literally just "found" anywhere.
Looking at found photography
Much of the appeal of found photography is the mystery regarding the original photographer or subject matter. Barry Mauer  lists four practices of looking that influence inferences made in regards to the origin of found photos; voyeurism, Sherlock Holmes' style deductive reasoning, Surrealism, and with the eye's of a cultural anthropologist. He describes the ideal found photography exhibit as inviting a viewer to sample all of these viewing practices in order to achieve two results: to force a viewer to consider the effect of their own perceptual process during their viewing and to build the widest spectrum of possible meaning within the limitations of found photography.
History of found photography
The history of found photography is not well documented because it most likely started as someone's hobby before being introduced to the art world, but even its first ventures into fine art are uncertain because the art community has not received found photography well, much like its predecessor found art.
Found photography actually falls underneath the umbrella of found art, which has its origins with Marcel Duchamp and his readymades in the 1910s. Since found photography utilizes found objects to generate artwork it is considered found art. However, the found art movement was about the decontextualization of art, where the form or shape of the artwork creates the meaning rather than the context. As such found photography treads a gray-line between found art and collage because of its relationship between form and context.
Found photography lacks the three-dimensional quality characteristic of found art but retains form as meaning since it is still a found object. Found photos also have meaning established by context that is a byproduct of being a photograph with an original narrative. However, the viewer is required to actively engage in viewing the photography, much the way they would found art, in order to unearth this context as meaning that will forever be limited by its unknown origins.
Thus there is great debate over whether found photography can be considered found art or if it is really a method of collage.
Found photography as art
Found photography is still so new and underground that there are not many arguments for or against the practice as art. Categorizing found photography as found art or collage broadens both the range of available arguments, and also the controversy. Whether or not found photography can be classified as art depends on the viewer's definition of art.
In Hegelian terms found photography is not art because the artist who found the photo did not embed meaning or spirit into it.
According to Dona Meilach, a found artist in the 1960s, found art, and in correlation found photography, is indeed art because of the artist's manipulation of the found materials. In the case of found photography, the way photos are exhibited by the artist affects the meaning viewers extract from them (refer back to Barry Mauer and Looking at Found Photography).
However, there are ultimately few examples of found photography as fine art. Some found photography artists include: Arianna Arcara and Luca Santese; two Italian photographers, founders of the collective * Cesura (photographers group) , that documented the U.S. economic crisis in Detroit using photos they found all over the city, Hans-Peter Feldmann, Joachim Schmid, Ted Adams; a Philadelphia photographer.
Found photography as a hobby
People are more likely to engage in found photography as a hobbyist or viewer looking at a hobbyist's collection. Unfortunately, these physical collections remain unknown while they require prior knowledge of its existence and geographical presence from viewers. However, with the creation of new online platforms for displaying photography there are now many online collections available for viewing. In fact the majority of these collections are based on viewer participation, where anyone with a found photograph can upload it for exhibition in the digital gallery. An example would be The Museum of Found Photographs, an open to the public Flickr page that pools members' found photos.
Filmmakers Lorca Shepperd and Cabot Philbrick present an important point about found photography hobbyists in their documentary Other People's Photos. They interviewed collectors around Chelsea Flea Market in New York City and concluded that found photography hobbyists usually collect pictures for two reasons: they like eccentric images of people doing odd things or wearing funny clothing, or they have personal reasons behind their choices so the photo collection becomes a validation of their history. In the both cases the hobbyist's reason becomes a unifying theme throughout his or her collection and this theme in turn becomes a way of looking at found photography. In this way it can be argued that found photography is art in the hands of professionals and amateurs alike.
In Argentina there is a facebook group dedicated to the collection of photographs found on the street called "Negativos Encontrados" with more than 15,000 members. You may see a documentary based on "Negativos Encontrados " in youtube. Official Site: negativoencontrado.com.ar 
- Mauer, Barry. “The Found Photograph and the Limits of Meaning.” Enculturation, Fall 2001. http://enculturation.gmu.edu/3_2/mauer/index.html.
- Fowkes, William. “A Hegelian Critique of Found Art and Conceptual Art.” The Journal of Aesthetics and Art Criticism 37, no. 2 (December 1, 1978): 157–168.
- Meilach, Dona Z. Collage and Found Art. New York: Reinhold Pub. Corp, 1964.
- “‘Other People’s Pictures’ : NPR.” NPR.org, n.d. http://www.npr.org/templates/story/story.php?storyId=1964382.
Fowkes, William. “A Hegelian Critique of Found Art and Conceptual Art.” The Journal of Aesthetics and Art Criticism 37, no. 2 (December 1, 1978): 157–168.
Stribling, Mary Lou. Art from found materials, discarded and natural. New York: Crown, 1970.
“Artintelligence » When Photography Took Centre Stage: Aspects of 1970s Conceptual Photography”, n.d. http://artintelligence.net/review/?p=706.
Meilach, Dona Z. Collage and Found Art. New York: Reinhold Pub. Corp, 1964.
“Flickr: The Museum of Found Photographs Pool”, n.d. http://www.flickr.com/groups/47255139@N00/pool/.
Ades, Dawn. Marcel Duchamp. World of Art. New York, N.Y: Thames and Hudson, 1999.
Philbrick, Cabot, and Lorca Shepperd. Other People’s Pictures. DVD, Documentary, 2004. http://www.other-peoples-pictures.com/trailer.htm.
“‘Other People’s Pictures’ : NPR.” NPR.org, n.d. http://www.npr.org/templates/story/story.php?storyId=1964382.
Mauer, Barry. “The Found Photograph and the Limits of Meaning.” Enculturation, Fall 2001. http://enculturation.gmu.edu/3_2/mauer/index.html.
“U.S. Copyright Office - Can I Use Someone Else’s Work? Can Someone Else Use Mine? (FAQ).” Government. Copyright, n.d. http://www.copyright.gov/help/faq/faq-fairuse.html.