Paranormal is a general term that designates experiences that lie outside "the range of normal experience or scientific explanation", or which indicates phenomena understood to be outside of science's current ability to explain or measure. Paranormal phenomena are distinct from certain hypothetical entities, such as dark matter and dark energy, insofar as paranormal phenomena are inconsistent with the world as already understood through empirical observation coupled with scientific methodology.
Notable paranormal beliefs include those that pertain to ghosts, extraterrestrial life and unidentified flying objects, and cryptids.
By definition, a ghost is a manifestation of the spirit or soul of a deceased person. Alternative theories expand on that idea and include belief in the ghosts of deceased animals. Sometimes the term "ghost" is used synonymously with any spirit or demon, however in popular usage the term typically refers to a deceased person.
A widespread belief concerning ghosts is that they are composed of a misty, airy, or subtle material. Anthropologists speculate that this may also stem from early beliefs that ghosts were the person within the person, most noticeable in ancient cultures as a person's breath, which upon exhaling in colder climates appears visibly as a white mist. This belief may have also fostered the metaphorical meaning of "breath" in certain languages, such as the Latin spiritus and the Greek pneuma, which by analogy became extended to mean the soul. In the Bible, God is depicted as animating Adam with a breath.
The possibility of extraterrestrial life is not, by itself, a paranormal subject. Many scientists are actively engaged in the search for unicellular life within the solar system, carrying out studies on the surface of Mars and examining meteors that have fallen to Earth. Projects such as SETI are conducting an astronomical search for radio activity that would show evidence of intelligent life outside the solar system. Scientific theories of how life developed on Earth allow for the possibility that life developed on other planets as well. The paranormal aspect of extraterrestrial life centers largely around the belief in unidentified flying objects and the phenomena said to be associated with them.
The second camp consisted of individuals who coupled ideas of extraterrestrial visitation with beliefs from existing quasi-religious movements. These individuals typically were enthusiasts of occultism and the paranormal. Many had backgrounds as active Theosophists, Spiritualists, or were followers of other esoteric doctrines. In contemporary times, many of these beliefs have coalesced into New Age spiritual movements.
A cryptid is an animal whose existence is not confirmed by science. The study of these creatures is known as cryptozoology.
Approaching the paranormal from a research perspective is often difficult because of the lack of acceptable physical evidence from most of the purported phenonema. By definition, the paranormal does not conform to conventional expectations of the natural. Therefore, a phenomenon cannot be confirmed as paranormal using the scientific method because, if it was, it would no longer fit the definition. Despite this contradiction, studies on the paranormal are periodically conducted by researchers from various disciplines. Some researchers study just the beliefs in the paranormal regardless of whether the phenomena are considered to objectively exist. This section deals with various approaches to the paranormal: anecdotal, experimental, and participant-observer approaches and the skeptical investigation approach.