Understanding the structures of today's wire and news service agencies requires some knowledge of the industry's long and storied past. From nearly the moment that photography was invented, news agencies have been around to help manage the public's access to photojournalism.

The three oldest agencies are Associated Press (AP), Reuters and Agence France-Presse (AFP), all of which are still thriving.

AFP was founded in 1835, followed by AP about a dozen years later and Reuters in 1851.

Around the turn of the 20th century, commercial picture transmission using radio waves began and, by 1921, Western Union began sending the first electronically transmitted photographs. A decade later, AP introduced a wire photo service, and the agency has dominated the field ever since. Most major city newspapers in the 1930s had an AP photo desk, staffed by an AP employee who received and printed photos for the paper and shared shots taken by the paper's staff with other AP members around the world.

With AP in New York, Reuters in London and AFP in Paris, photographers began furiously submitting news images for their agencies to distribute globally. The big three cashed in on the fact that a single image could now be quickly reproduced hundreds of times in one day.

As news photography was spurred on by further advancements in telephone transmission of images, a new breed of photojournalistic entrepreneur arose to take advantage of the demand for newsworthy photos. Photographers who wanted control over their images began forming alliances with reps who knew the business andpromoted photo stories as packaged sets. In 1946, photographers Robert Capa, Henri Cartier-Bresson, David Seymour and George Rodger formed Magnum Photos, a cooperative agency that was owned by all of its members, a model that many other agencies tried to emulate.

Over the next 30 years, numerous news-oriented photo-story agencies were launched, such as Black Star, Contact Press Images, Gamma Liaison, Matrix, Saba, Sipa Press and Sygma.

These reportage-style boutique agencies significantly advanced the photo-story cause. They fought for rights and day rates as their photographers covered wars, natural disasters, and poverty and human rights issues, often on a self-assigned basis.

As government censorship laws relaxed following World War II, the public was able to view some of the most gripping and hardhitting images of the century. In those analog days, film flew back and forth across continents to labs and service bureaus, and news publications were busy competing with the recent innovation of live television.

In the mid- to late-1960s, AP started using faxes to transmit photos, which saved costs but compromised quality. Papers also received photos from the now-defunct United Press (UP) and International News Service (INS), but many syndicates sent prints though the mail. "We had access to hundreds of photos every day, even some in color, and way more than we could possibly use," recalls Wilson Locke, news editor at The Oakland Tribune and then The Los Angeles Times from 1957 to 1991. When scanning technology was introduced, newspaper conglomerates such as The New York Times News Service, Knight Ridder and Tribune Media Services got into the business of recycling their daily photo contributions.

During this period, news and feature magazines were still presenting photographs the way they were meant to be seen: reproduced large and untouched, with noticeable credits for the shooters. Photojournalists were starting to be in demand by name, but the rules of engagement were about to change.

By the late 1980s, a more technical world had emerged, and soon a giant web was holding everything together. Internet-born photo agencies Corbis and Getty Images recognized that photography was the perfect digital vehicle.

Leading the way with stock shots galore, they also wanted that editorial edge and went after it obsessively. When the dust settled, Corbis had bought Sygma and Saba, and Getty had claimed Gamma Liaison. Both agency giants spent fortunes on shooters, strategies and technologies to make sure that news photos could be delivered hourly to the monitors of picture editors everywhere.

It is in this daunting environment, in which only a few huge photo conglomerates and wire services have been left standing, that today's new independent agencies are forced to compete.