What is the seriousness of bullying?

Bullying can be a very serious matter, depending on the severity of it. Harmless taunts and insults like "you suck", or other friendly banter won't be considered very serious. However, if someone is to constantly insult another person in an alarming way, such as death threats and physical actions against the person, it can be considered very serious.

In another way of taking the question, it is a very serious problem in the world, and from what I have seen in my research on it, not nearly enough is being done on it.