Stock photography is when you take commercial photographs, but where there is no one customer commissioning you for the photographs. The photographs are typically placed on a stock photography website, such as iStockPhoto, and sold to many customers. Customers will use these images for their websites, for magazine ads, etc.
A typical stock photo you’ve probably seen is of a pretty young woman answering a helpline, which would be used on many websites for their “support” web page. It could also be pictures that convey business concepts, such as teamwork, frustration, meetings, etc., or it could just be a picture of a couple lying on a beach, which would be used by a travel agency.
One of the premiere photographers in Stock photography is Yuri Arcurs. He has great tips in the form of videos on his YouTube channel. He not only shows tips for the photographer, but useful information for models who want to do stock photography.
Take a look at this video, and you can see his other videos from the same YouTube page.