Believe it or not!
What's a hoax?
A hoax is a picture or statement over the internet that has a story or a photoshopped picture that is believable but not real. They are used to trick people as a joke but can turn out to be very wrong in many cases.
How to tell
Sometimes it is fairly easy to tell if a picture is a hoax if the photoshop is bad. Bad photoshopped pictures usually have colors or maybe cropped areas of the photo that look strange. Even in hoax stories you can tell which parts of it are exaggerated and fake.