Where do celebrity blog sites get their pictures of celebrities and how do they post them legally?

I wanted to start a blog about celebrities and I wanted to know where other celebrity blogging sites get their original pictures of celebrities and if they get them from external sources, how do they prevent doing this illegally and/or plagiarizing?

I think they’re all signed up to ‘Getty images’, you can get all the latest pics of any celeb you want there…but you need to pay for it..and then to make them legal they have to credit where you got the picture from at the bottom of the post.. it’s usually in tiny writing so you probably don’t even notice it..

i’m not sure but i think so.. hehe