Why did the witch hunts begin?

People started seeing things and blamed it on black magic. People thought some women were to blame for this black magic. The people called them witches. People were suspicious about these women. People started questioning who was a witch, so they had a poorly thought out method: she would be dunked in a river, if she sunk and died then the citizens knew that she wasn't a witch. But it was too late. If a women floated then they would burn her at the stake. If she survived this she was to be hanged.

In fact, there are no known cases of anyone who was accused of being a witch being burned at a stake. This is a popular misconception.