Bullying is unwanted aggressive behavior among school-aged children that involves a real or perceived power imbalance. It is repetitive and can seriously harm both the children being bullied and those who bully. Bullying includes verbal threats, spreading rumors, physical attacks, and social exclusion. While teasing is sometimes part of childhood, it becomes bullying when it is repetitive or intended to hurt. Bullying affects 20-30% of school children and can begin in preschool, intensifying during transitions like starting middle school. Victims often have low self-esteem and poor social skills, making them targets. Both bullies and victims can suffer long-term effects on mental health, relationships, and academic performance. Warning signs in children include