Bullying occurs when a child or children repeatedly harass, intimidate, hit, or shun another child who is weaker physically or has less social standing. Bullying often involves verbal or physical aggression and may include hitting, shoving, or taking money or belongings.

Boys tend to engage in physical intimidation (hitting or threatening to hit) as well as verbal insults, and they often act one on one. Girls tend to bully in groups by shunning another girl or gossiping about her. Adults can engage in bullying each other, but the behavior more commonly occurs among children and adolescents.

Repetition is necessary for bullying. An isolated fight between two children of similar size and social power is not bullying; neither is occasional teasing.

Bullying can be stopped through the coordinated efforts of parents, teachers, school counselors, and sometimes psychologists or psychiatrists. Many schools have zero-tolerance policies regarding bullying and teach children that such aggression will not be tolerated.