I'm frequently asked whether it's ok to copy a picture found on the Internet, and use it on a website, or in a newsletter. My answer is always the same: "not unless you have permission." The reason is this: making an unauthorized copy of someone else's work is copyright infringement, and can subject you to substantial damages - up to $150,000 per work infringed, in extreme cases.
If you want to use a photograph, you need permission from the copyright owner. And the owner of the copyright in a photograph is not the subject of the photograph, but the person who presses the shutter button.
This issue was addressed last year in a funny case involving a selfie taken by a monkey.