In sociology, a stigma is something that prevents a person from being accepted into normal society. According to Irving Goffman, there are three types of stigma: character, physical and group association.
Character stigmas are stigmas placed on people based on some aspect of their character. These types of stigma are usually dictated by a common system of moral values by which society measures character. Physical stigma is stigma that is placed on people based on their physical appearance. Deformity and unusual appearance are examples of physical stigma. Group association stigma is a type of stigma placed on people based on their classification within a group. This could be a religion, an ethnicity or even a political group. According to Goffman, group association is usually attached to entire families and is passed through generations.
Stigma is usually the result of fear of things perceived as abnormal. Some people try to eliminate the stigma by altering either their character or physical appearance. Others form a new "normal" by associating with other people who have stigma attached to them. Sometimes people try to deflect stigma by presenting an image of themselves that is intended to draw attention away from what is perceived as an abnormality.