Bullying is the repeated use of aggression by one or more people against another person or group. Bullying usually involves an imbalance in power, in which the bully is bigger or stronger than his or her target. Bullies may abuse their victims verbally, physically, or psychologically. Bullying may involve name-calling, pushing or hitting, or preventing an individual from joining a social group or participating in an activity. Bullying occurs from the preschool period through adulthood, though it most often occurs during early adolescence.