Answer:
Several centuries ago, many practicing Christians, and those of other religions, had a strong belief that the Devil could give certain people known as witches the power to harm others in return for their loyalty. A "witchcraft craze" rippled through Europe from the 1300s to the end of the 1600s. Tens of thousands of supposed witches—mostly women—were executed. Though the Salem trials came on just as the European craze was winding down, local circumstances explain their onset.
In 1689, English rulers William and Mary started a war with France in the American colonies. Known as King William's War to colonists, it ravaged regions of upstate New York, Nova Scotia and Quebec, sending refugees into the county of Essex and, specifically, Salem Village in the Massachusetts Bay Colony. (Salem Village is present-day Danvers, Massachusetts; colonial Salem Town became what's now Salem.)