Human beings are categorized into a number of races, based on their geographical location, physical characteristics, culture, language and history. It is a social concept, not biological. For example, in America, there are Caucasians, African-Americans, Asians etc who differ from each other physically. However, being different no way makes a race superior or inferior to another. Yet, there are certain people who think, believe and act in ways that suggest that their race is superior to others. 'Racists' as they are referred to, are prejudiced and if you look at history, they have even resorted to violence against the races they considered inferior. People are not born racists, it is a learned behavior.