Unidentified flying object

An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon. Culturally, UFOs are associated with claims of visitation by extraterrestrial life or government-related conspiracy theories, and have become popular subjects in fiction. UFOs are often identified after their sighting. Sometimes, however, UFOs cannot be identified because of the low quality of evidence related to their sightings.
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