Bullying, sometimes called mobbing, is a form of conflict escalation. This is the systematic (direct or indirect) attitude of hostility, harassment or discrimination against individuals within groups by other group members (single or multiple) or supervisors.
In order to be called bullying, such behavior has to happen frequently and over a longer period of time. Bullying is often made up of many small events that are not destructive in themselves, but in their entirety cause great harm to those affected. The goal or effect of bullying is often the exclusion of individual members from the community (the team, the company, the school class).