
Recent commentators have used different ways to describe bullying behavior, but they agree that a bully is only interested in maintaining his or her power and control. Because bullies are cowards and are driven by deep-seated insecurities and fears of inadequacy, they intentionally wage a covert war against an organization's best employees - those who are highly-skilled, intelligent, creative, ethical, able to work well with others, and independent (who refuse to be subservient or controlled by others). Bullies can act alone or in groups. Bullying behavior can exist at any level of an organization. Bullies can be superiors, subordinates, co-workers and colleagues.
Some bullies are obvious - they throw things, slam doors, engage in angry tirades, and are insulting and rude. Others, however, are much more subtle. While appearing to be acting reasonably and courteously on the surface, in reality they are engaging in vicious and fabricated character assassination, petty humiliations and small interferences, any one of which might be insignificant in itself, but taken together over a period of time, poison the working environment for the targeted individuals...
Bullying is not about a "clash of personalities," a "misunderstanding," or "miscommunication." According to two psychologists who have conducted surveys on bullying, (1) bullies use surprise and secrecy to gain leverage over those targeted, (2) they are never interested in meeting someone else halfway so trying to negotiate with a bully is useless, (3) they routinely practice psychological violence against specific individuals whom they intentionally try to harm which is devastating to the targeted person's emotional stability "and can last a long time."
From: http://gbr.pepperdine.edu/014/bullies.html