Cyberbullying is bullying committed using the internet, specifically defined as repeated and deliberate acts of harm and harassment against specific individuals carried out via information technology networks. It is the single biggest abhorrence plaguing the internet to this day. As committed by adults, cyberbullying is more severe than trolling, which is by its definition short-term and/or indiscriminate, and is by definition systematic, long-term and personalized; one-off hostile remarks do not count.
Cyberbullying may include false accusations, stalking, impersonation and identity theft, threats, and hate "art", richly-designed media targeting specific individuals. Cyberbullies often use illegal means to hide their identities, making it difficult to punish them, by legal processes or otherwise.
- Wikipedia has a fairly comprehensive and accurate page as of now.