The world is a very busy place! Businesses of every kind need fresh content to stay competitive.
Imagine all of the billions of blog's and websites on the internet. They constantly need new fresh photographs to help them stand out.
What about the tens of thousands of newspapers and magazines worldwide. They too are looking for photographs to help their articles stand out.
This is where you come in!

Selling stock photography is as easy as taking a photograph and uploading it to a stock photography company. In most cases you will be loaning or licensing your photograph(s) to them them for reproduction on websites, magazines and newspapers.
Imagine for a second if you owned a newspaper in Arizona and you were doing a story on Orange crops in Florida.
It would be quite costly to hire a photographer, book a flight, and send them off to Florida to get the photos you need for your website of oranges and orange growers in Florida. Instead through stock photography, websites can get the pictures they need without all the extra cost of hiring a professional photographer to travel to a location.
For you the photographer you'll sell your pictures to these companies who desperately need new images for their businesses.