A cyber-bully is a person who bullies others online, using various platforms such as chat rooms, emails, texting, etc. They engage in harmful behavior, such as sending threatening messages, spreading rumors, or posting derogatory comments, with the intention of causing emotional distress to their victims. This form of bullying can have severe psychological effects on the individuals targeted, as it can happen anonymously and reach a wide audience, making it difficult for victims to escape or seek help.