When I find a photo somewhere on the internet, without any explicit information of whether I can re-publish it on my own website, without any hint of who is the owner/author of that photo, can I still do it? I'm puzzled here cause I've seen like millions of websites, often very big, that repost photos, most probably found via google and it's VERY unlikely they bothered to look for and contact the author of that photos. Is every one of that sites likely to be sued at any moment? What about the case of forums and content provided by users - there is virtually no way of prevention here.