How to import photos from Facebook?

Question

I noticed when I visit photo printing websites, they ask you if you would like to import your photos from Facebook. How do they do it? Does Facebook provide API to import us

Answer 1

When I did it they logged in on my behalf (I put in my user/password) and navigated photo albums by expected HTML.

There were some legal things I had to "accept" and was notified of what they would do with my details.