This article is from the Alien Visitors FAQ, by CRAM: The Cyberspatial Reality Advancement Movement ldetweil@csn.org with numerous contributions by others.
A UFO is an Unidentified Flying Object.
It is "Something seen in the sky (or on the land, or expceptionally in the
water, but thought capable of flight) which the witness could not identify
and thought sufficently strange to report to either an offical or unoffical
investigating body".
A UFO is the stimulus for a UFO report made by a UFO witness. UFO researchers
(often called UFOlogists) study UFO reports and witnesses. UFO researchers
cannot directly study UFOs. There are some reports in the literature of
different governments recovering craft thought to cause UFO reports, but most
of these reports are speculative. The study of UFO reports is referred to as
UFOlogy. This implies a scientific basis to the study, when in practice very
little scientific research is carried out. After careful investigation about
90% of all UFO reports can be reasonably explained as either natural phenomena
or misidentification of normal manmade devices. Sometimes the term IFO is
used for these Identified Flying Objects. Those cases which are identified
as natural phenomena are often rare or short lived and are worthy of study
in their own right.
In the early days of investigation used interchangably with the term 'Flying
Saucer'. More recently the term Flying Saucer has fallen into disuse,
although some researchers use it as a term to specifically refer to an
extraterrestrial spacecraft.
 
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