Argumentum ad populum

Argumentum ad populum is a type of argument people can use to convince other people of something. It means "argument to the people", and it's when somebody tries to convince someone else of something by saying that lots of other people also believe it. For example, if you say "lots of people believe that ghosts exist, so it must be true," then you're using argumentum ad populum.
Instead of using evidence to show that something is true, argumentum ad populum relies on people believing something just because it’s popular. It does not work because popular things are not always true.