A photo stock agency acts as a middle man between photographers and stock photo buyers. The agency may have a broad audience of potential buyers for the photos, and in some cases can negotiate the costs for the photographers. Names for the collection of photos at a photo stock agency include: picture library, photo bank, image bank, and photo archive, amongst others.
Prices of images at a photo stock agency may vary from around $1 up to several hundred dollars, depending on the type of image, its quality, and other factors. Lesser costs are often associated with microstock photography, which is a subset of normal stock photography in which most images are sold over the Internet, and a wider ranger of photographers, including amateurs at times, are drawn from.
There are two major types of stock photos as far as licensing is concerned: royalty-free and rights-managed.
Royalty-free (RF for short) means that no royalty, or fee, needs to be paid upon each use of the image. The term does not mean that the photo is public domain, or free to use without the purchase of a license for it. Generally, a royalty-free stock photo still has some limit on how many times it may be used by the buyer, although there is not typically a time limit during which those uses may take place.
Rights-managed (RM for short) means that the stock photo is licensed for a particular use, or several uses. The cost of the license may vary depending upon the particular uses, the quantity or duration of use, the territory, the image itself, and other factors. Magazines and other publications or businesses with large print runs may find themselves unable to use royalty-free images, and instead required to go the rights-managed route, unless they have their own photographers.
Royalty-free and rights-managed also differ in the sense of exclusivity. With RF stock photos, the photographer may sell the rights to use the images multiple times, whereas with RM images, generally no other individuals or organizations may use the photos in a conflicting way. Rights-managed items may also be exclusive to one buyer, in some instances.
Several of the more popular photo stock agencies online are: Jupitermedia Corporation, Shutterstock, and iStockPhoto. More traditional photo stock agencies include Getty Images, Corbis, and others.