Getty Images and Corbis are the two largest traditional stock photography agencies in terms of revenue. They offer mostly photographs that have been shot by professional photographers. There are many alternative photo agencies which enable amateur and professional photographers to offer their photographs for sale. These are known as microstock photography services, because photographs sell more cheaply but in greater volume.

Images are filed at an agency that negotiates licensing fees on the photographer's behalf in exchange for a percentage, or in some cases owns the images outright. Pricing is determined by size of audience or readership, how long the image is to be used, country or region where the images will be used and whether royalties are due to the image creator or owner. Often, an image can be licensed for less than $200, or in the case of the microstock photography websites as little as $1 for a low resolution license.

With Rights Managed stock photography an individual licensing agreement is negotiated for each use. Royalty-free stock photography offers a photo buyer the ability to use an image in an unlimited number of ways for a single license fee. The client may, however, request "exclusive" rights, preventing other customers from using the same image for a specified length of time or in the same industry. Such sales can command many thousands of dollars, both because they tend to be high-exposure and because the agency is gambling that the image would not have made more money had it remained in circulation. However, with royalty free licensing there is no option for getting exclusive usage rights.

Some stock photography sites offer low-resolution photography free for the purpose of preparing advertising comps to demonstrate a design. If the advertiser decides to use the image, the rights to use the high-resolution image then can be negotiated or purchased directly from the website.

Professional stock photographers place their images with one or more stock agencies on a contractual basis, with a defined commission basis and for a specified contract term. Some photographers fund their own photo shoots, or develop imagery in cooperation with an agency, while others submit photographs originally produced as part of editorial (magazine) or commercial assignments.

"Free" in this context means "free of royalties (paying each time you use an image)". It does not mean the image is free to use without purchasing a license or that the image is in the public domain.

(sometimes called "licensed images")

Newspapers and magazines were first able to reproduce photographs instead of line drawings in the mid-1880s with the invention of the half-tone printing press. Initially starting with staff photographers, eventually independent free-lance photographers took over.

One of the first major stock photography agencies was founded in 1920 by H. Armstrong Roberts, which continues today under the name RobertStock.

For many years, stock photography consisted largely of outtakes ("seconds") from commercial magazine assignments. By the 1980s, it had become a specialty in its own right, with photographers creating new material for the express purpose of submitting it to a stock house. Agencies attempted to become more sophisticated about following and anticipating the needs of advertisers and communicating these needs to photographers. Photographs were composed with more of an eye for how they might look when combined with other elements; for example, a photo might be shot vertically with space at the top and down the left side, with the conscious intention that it might be licensed for use as a magazine cover.