Microstock photography, also known as micropayment photography, is an offshoot of traditional stock photography. What defines a company as a microstock photography company is that they (1) source their images almost exclusively via the Internet, (2) do so from a wider range of photographers than the traditional stock agencies (including a willingness to accept images from "amateurs" and hobbyists), and (3) sell their images at a very low rate (anywhere from $.20 - $10) for a royalty-free image.
A number of microstock sites also sell vector art, and some sell Flash animations and video, as well as images.
There is no fee to post photos on a microstock site. However, microstock companies do not accept everyone or all photographs. Each employs a team of reviewers who check every picture submitted for technical quality, as well as artistic and commercial merit. Photographers add keywords that help potential buyers filter and find pictures of interest.
The mindset of microstock supporters is that quality will prevail and photographers will end up making as much from many small sales as they would from a few large sales on a traditional stock photography site. But some professional photographers believe microstock devalues the practice of photography, since most pictures on microstock sites have been taken by non-professional photographers. Professional photographers see the growth of microstock sites as reducing their own incomes.
In April 2008, Focal Press published "Microstock Photography: How to Make Money from your Digital Images" written by Microstock library contributor Douglas Freer, which is the first hard copy book to deal exclusively with the Microstock library phenomenon.