Paranormal means something other than normal and cannot be explained by science. Notable paranormal beliefs include those that pertain to ghosts, demons, extraterrestrial life, and unidentified flying objects.

Supernatural uses themes that contradiction the commonplace natural world and materialist assumptions about it. Supernatural fiction includes vampire literature and the classic ghost story. Characters can include any supernatural being such as vampires, werewolves, ghosts, angels, gods, etc. Supernatural fiction continues to be popular, but because it is not simple to define and is not popularly understood.

Fantasy uses magic and other supernatural phenomena as a primary element of plot, theme, or setting. Many works within the genre take place in imaginary worlds where magic is common. Fantasy has included wizards, sorcerers, witchcraft, etc. in events which avoid horror.

Science Fiction includes imaginative but more or less plausible content such as settings in the future, futuristic science and technology, space travel, parallel universes, and paranormal abilities. Its imaginary elements are largely possible within scientifically established laws of nature. Characters include aliens, mutants, androids, and humanoid robots. Some settings may be other universes and dimensions, alternative timelines, the future, or a historical past that contradicts known facts of history.

Alternate history is set in worlds in which one or more historical events unfold differently than it did in the real world. Alternate History looks at "what if" scenarios from some of history's most pivotal turning points and presents a completely different version, sometimes based on science and fact, but often based on conjecture.

You will notice that some genres seem to share definitions. If you have any other examples or would like to add to the definitions, please do so in the comments.