Several magazine covers dedicated to research on UFOs or aliens.

The word alien originates from Latin, formed by the combination of alienus ("foreign," "strange," or "belonging to another") and genus ("origin" or "birth").

Many scientists consider extraterrestrial life plausible, but there is still no direct evidence of its existence. Since the mid-20th century, there has been a continuous search for signs of extraterrestrial life. The topic has also played an important role in works of science fiction.