What are Ghosts?

They have been in movies and on television for years. You hear stories throughout your childhood about them, and you have probably seen some pictures with them in it. But what are they? The answer is, nobody knows for certain. Some people just say that they are spirits of the deceased, stuck on Earth. Others say that they are demons from hell. The truth is that there are many theories about what ghosts are, but nobody can really find out. Although many people claim to have seen ghosts, most of those "stories" are untrue, and can be proved wrong by simple science and technology. But on some rare occasions, there are a few stories that can't be proved false.