The paranormal can be defined as anything that it outside the realm of what we can explain using scientific methods. The word itself is made up of the Latin word para, which means "outside," and normal. This term can be used to describe several different kinds of phenomena, including ghosts, ESP, cryptozoology, and UFOs.
When people think about the paranormal, the subject of ghosts is one that usually comes to mind right away. Most cultures believe in some form of the afterlife, with the accompanying idea that a person is made up of a spiritual as well as a physical body. A ghost is a manifestation of the person's energy or spirit seen after their death.
Skeptics allege that ghosts are not real, and that there are other explanations for reported sightings. They point to the power of suggestion playing a role in the paranormal and that people are more likely to report having seen a ghost while visiting a place where similar events have taken place. While investigation of ghost sightings does often point to an alternate explanation, there are a certain number of experiences that cannot be readily explained. These ones remain in the realm of the paranormal.
ESP, or extra sensory perception, refers to receiving information from sources other than the five senses: sight, sound, smell, touch, and taste. It is sometimes referred to as a "sixth sense." People with psychic abilities use them to access information about the past, present, or future that others are not able to. These skills are lumped in with the paranormal, even though some people feel that they are something that everyone is born with and only need to be practiced to be developed more fully.
Cryptozoology is the search for and study of animals whose existence has not been confirmed by science. Creatures like the Loch Ness monster and Bigfoot fall under this category. Several animals who were originally thought to be legendary or hoaxes turned out to be very real, and that fact is something that cryptozoologists point to when defending their work. For example, the duckbill platypus was thought to be a joke when the first carcass was sent to England for examination by scientists. We now know that this unusual animal is very real.
UFOs, or Unidentified Flying Objects, are another subject that forms part of the realm of the paranormal. People have reported seeing strange lights in the sky and some accounts report seeing actual crafts that that are very different from any known aircraft. Many of these reports are explained as being weather balloons or some other benign object, but there are still a small percentage of sightings that can't be readily explained by science.