Can I sell my photographs to Istock?

I came across their website. I myself own a Nikon D5000 and take pictures as a hobby. I was wondering if I could sell some of my pictures t them? Because it seems like that's what some people are doing. Is there something I have to qualify for?

Yes you can

Yes you can sell your pictures to them, but they do have a lot of agreements to make before you could finally be a contributor which is really good. They also have this quiz to see if you really have understood all their photo requirements.