UFO is an acronym for Unidentified Flying Object. Such objects include meteors, disintegrating satellites, flocks of birds, aircraft, lights, weather balloons, and just about anything moving within the visible band of electromagnetism. In common language UFO has been often a synonym for an alien spacecraft.
There are many photographs of UFOs and they are of equal quality: blurs and forgeries. Other physical evidence, such as alleged debris from alien crashes, or burn marks on the ground from alien landings, or implants in bodies of alien abductees, have turned out to be quite terrestrial, including forgeries.
UFOlogy is the mythology of the space age. Rather than angels...we now have...extraterrestrials. It seeks to give man deeper roots and bearings in the universe. It is an expression of our hunger for mystery...our hope for transcendental meaning. The ancient gods have been transformed into space voyagers.