Usually defined as negative feelings towards persons based on membership in a social group, such as racial prejudice. However, logically speaking prejudice can consist of positive feelings, which does not lead to societal problems. Obviously stereotypes and prejudice are related.
Discrimination is the behavioral component.
Different treatment of individuals based on group membership. Not necessarily conscious or intentional. A person may behave in a racist or sexist way without being aware of this. Throughout the history of research on stereotypes, discrimination and prejudice, psychologists' views have changed. There was the belief in the inherent superiority of white males.