Answer:
Witch hunts were series of trial conducted by European government to execute the people who were suspected of engaging in Witchcraft (Some sort of dark magic that's banned by the church).
Many of the people at that time still believe in superstition.
So, when there's a suspicion of witchcraft activities in their community, a lot of people were scared and panicked. This caused a massive disruption in a lot of communities during the renaissance.
On top of that, Many people who were condemned during the witch trial were actually innocent. Many people who have simple mental disabilities were considered 'cursed' by witchcraft since the people at that time didn't really study psychology as a science.