Can you share a picture that you found on social media or a website (or in Google image search)?
This infographic answers that:
"While the laws about distributing images through social media channels likes Facebook, Pinterest, Google+, and blog are still fuzzy, it is generally considered acceptable to redistribute an image that was originally intended to be publicly viewed by the creator. This is why you will typically find original images re-posted on blogs, news sites, and social networking sites even if the person re-distributing the images didn't obtain permission to do so....
Via Jeff Domansky