Founded in 2000 by Bruce Livingstone, iStockphoto (at first) was set up as a free stock image website. As time progressed they switched to a paid credit based system. In 2006 iStockphoto was acquired by Getty Images for the sum of $50 million, they remain to operate independently (with al the benefits of Getty Images).
 
After Stockxpert’s closure (also a Getty owned agency), all users are now redirected to iStockphoto for credit based downloading and their new website Thinkstock for subscription based downloading. This makes them one of the largest agencies and a direct competitor for Shutterstock.

iStockphoto application process
To register, you will need to take and pass a small quiz which (with some common sense and knowledge about microstock) will not be to hard. If you are not certain about yourself, then you should follow their training tutorial. After that you will be asked to upload your photo id (passport recommended) and 3 photos so they can review the quality of your work.

My performance
See how I perform on iStockphoto by viewing my monthly microstock earnings reports!

iStockphoto details / statistics