Cyberbullying is the use of the Internet and related technologies to harm other people, in a deliberate, repeated, and hostile manner. As it has become more common in society, particularly among young people, legislation and awareness campaigns have arisen to combat it.

The term "cyberbullying" was first coined and defined by Canadian educator and anti-bullying activist Bill Belsey, as "the use of information and communication technologies to support deliberate, repeated, and hostile behavior by an individual or group, that is intended to harm others."

Cyberbullying has subsequently been defined as "when the Internet, cell phones or other devices are used to send or post text or images intended to hurt or embarrass another person". Other researchers use similar language to describe the phenomenon.

Cyberbullying can be as simple as continuing to send e-mail to someone who has said they want no further contact with the sender, but it may also include threats, sexual remarks, pejorative labels (i.e., hate speech), ganging up on victims by making them the subject of ridicule in forums, and posting false statements as fact aimed at humiliation.