From Abracadabra to Zombies
In a nutshell: Area 51 is a military base that some people think is used to hide aliens and their spaceships.
"Area 51" is part of an off-limits military base near Groom Lake, a dry salt flat in Nevada. Some people say that Area 51 is used to hide aliens from us and to try to make copies of their spacecraft.
At one time the government did not even admit there is an Area 51. In 1997, the military admitted there is an Area 51, but the area is still off-limits to anyone not in the military. Even many military airplanes aren't allowed to fly over it.
Skeptics don't doubt that something secret is going on in Area 51. Area 51 might be an illegal dumping ground for poisons and radioactive waste. Several former workers at Area 51 and widows of former workers have filed lawsuits against the government for injuries or death resulting from illegal hazardous waste practices.