In an article written for the J. Allen Hynek Center for UFO studies, Michael Swords describes Close Encounters of the First Kind (CEI) as "an incomplete form of knowledge"1. A Close Encounter of the First Kind is a type of UFO sighting, different from Daylight Disks, Nocturnal Lights and Radar Sightings because it is a UFO sighting at a distance of 500 yards or less, while the afore mentioned three may appear at great distances from the UFO spotter.
J. Allen Hynek first categorized close encounters in his book, the UFO Experience (1972) as Close Encounter of the first kind (CEI), Close Encounter of the Second Kind (CEII), and Close Encounter of the Third Kind (CEIII). In the beginning, CEIs included all UFO sightings. A Close Encounter of the Second Kind occurs when physical traces of a UFO are found. The third type of close encounter was later made popular by writer/director Stephen Spielberg in the movie, Close Encounters of the Third Kind (1977). A CEIII occurs when humans actually come into contact with extra-terrestrial beings2, 3.
During Project Bluebook, one of the US Government UFO research initiatives, the categories were expanded to specify long-distance sightings during daytime, nighttime, and radar "sightings"2 of UFOs.
Although history documents many reports of close encounters of every kind and some remain unexplained, to date, no close encounter has been proven to be a genuine close encounter with extra-terrestrial beings.
1. Michael Swords. “Fear, Sanity, and Crossing the Line.” J. Allen Hynek Center for UFO Studies 2007. 18 Oct 2008 <http://www.cufos.org/abduct_P2.html>.
2. “CIA's Role in the Study of UFOs, 1947-90 — Central Intelligence Agency.” https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/csi-studies/studies/97unclass/ufo.html.
3. “Close Encounters of the First Kind.” TinWiki.org 3 May 2008. 18 Oct 2008 <http://tinwiki.org/wiki/Close_Encounters_of_the_First_Kind>.
taken from: "Paranormal-Encyclopedia.com"