Another thing I looked up is Terms of Service. I just found out that the reason Pinterest, Tumblr, Imgur and similar sites can avoid copyright infringement is because they are using user-generated content. Which mean they do not take responsibility for them (says so in their ToS 'Limitation of Liability and Indemnity' clauses.
2. If I let users upload images to my site, can I also protect myself against infringement by adding a "Terms of Service"?
I did search and read on Wikipedia, but english ain't my native language and there are lots of jargons and words smart people use. Besides, I'd like some input from people.