Just as a follow on to the answer above.  In addition to the important points made above, we need to remember that the Puritan belief system that informed the inhabitants of Danvers (Salem), MA, in 1692, encouraged people to believe that evil, in the person of the Devil, was not merely an abstract concept but a real and physical threat to their well-being.  

The Devil as an active force in their society had, according to their Puritan belief system, the ability to make people ill and die, to make livestock sicken and die and, perhaps more important, invade people's minds with evil thoughts--often through dreams--that caused them to act out those thoughts.  As you can see from the results of the Witch Trials and executions, Puritans believed that girls and women were more susceptible to the Devil's influence than men (as daughters of Eve), and so the violence inflicted by the judicial system fell on women to a much greater degree on men.

Many of the accusations of witchcraft were based on what is called "spectral evidence."  In other words, the girls who were originally "afflicted" by the witches' torture accused people on the basis of seeing their spirits performing the torture.  Because there is no way to defend yourself effectively against such evidence--you can be two places at the same time--the accusations had weight in court.  It wasn't until 1693, when Increase Mather wrote a tract against the admission of spectral evidence, that this type of evidence became suspect in court.

For much of the witch trials, juries included the most important (land owning) church members.  As the concept of spectral evidence weakened, the courts began to allow juries to be made up of ordinatry church members (not necessarily the most wealthy), and these juries were more likely to exonerate the accused.  Also, toward the latter part of the witch hysteria, the wife of the Governor of Massachusetts Bay was accused, and that went too far.  Soon after this, the witch trials were ended.

The witch trials ended in part because spectral evidence became suspect; juries were no longer made up of only the richest, most powerful people in the community; and perhaps most important, the society became truly horrified by the results of the trials.

The significance of the Salem Witch Trials of 1692 remain a memorable and highly significant event in American history for what they foretold about the fragility of society in the face of a perceived threat.  Started when a village doctor pronounced the ailment that had afflicted relatives of the local Reverend, Samuel Parris, as having been caused by witchcraft, by the end of the panic and trials that ensued, 200 people had stood accused of witchcraft, 20 of whom were executed and many others imprisoned under harsh conditions.  At its core was resentment and fear of an influx into the village of Salem of refugees from nearby conflicts involving the English Crown.  The tensions between residents and newcomers were palpable and the seeds of conflict were planted.  Reverend Parris, noted for his stringent demeanor and questionable ethics, began to introduce the notion of Satanism into the conflict between natives of Salem and the newcomers.  The ensuing illness of his daughter and niece provided Reverend Parris the opportunity to exploit the young girls’ illnesses for political gain.  With the connivance of local magistrates and the town physician, the blame for the illnesses was attributed to the demonic presence within some of the destitute women refugees.

The Salem Witch Trials have come to represent the kind of mass paranoia and xenophobia that can inflict communities under duress.  When times become difficult, many seek people to blame, and it is not difficult to arouse the kinds of passions within a group of already frightened people against those accused of causing hardship.  The Salem Witch Trials were a precursor to a pattern that would be repeated around the world for centuries, including in the United States. 

In 1953, the eminent American playwright, Arthur Miller, published his play The Crucible, which took place during the Salem Witch Trials, and which is widely believed to have as a subtheme the paranoia regarding communism that had taken hold in America and resulted in the blacklisting of anyone suspected of Communist Party ties.  The parallel between the two periods in American history and the timing of the play’s publication certainly point to such an association.  Miller’s story of the Salem witch trials, occurring concurrently with the Red Scare and “witch hunt” for communists within American government and society was an early, and particularly influential allegory for the hysteria that can afflict entire populations if the conditions are right and the wrong leaders rise to the top.  Today, conservatives often use the metaphor of witch hunts to rail against those who they believe seek to silence them, including conservative talk radio.  The Salem Witch Trials have become a metaphor for American society at its most paranoid and self-destructive.  In that sense, the significance of those acts in 1692 remain as salient today as they did when Arthur Miller illuminated the historical parallel between 1692 Salem and early 1950s Washington, D.C.