Vote brigading

Vote brigading is massively coordinated online voting. It refers to the practice of affecting reviews or scores on websites that feature crowdvoting (e.g. online stores, review websites) by calling on large numbers of people to submit reviews, thereby boosting or decreasing ratings. This may be done for political reasons, like harming the credibility or commercial prospects of films dealing with controversial or sensitive subjects. Vote brigading is a form of participation bias, which can decrease the reliability of the aggregated score.