Stereotypes: What Is A Sterootype Threat?

First of all, what is stereotype threat? According to http://www.reducingstereotypethreat.org/definition.html, they say that "stereotype threat refers to being at risk of confirming , as self-characteristic, a negative stereotype about one's group". In my own words, stereotype threat is a negative assumption that someone says about another person. For example, some people say that all Asians are smart, white people are rich, blondes are dumb, or Mexicans are rapists and drug dealers. Throughout the research I've found, I learned that many people can get offended by the negative comments, and also how stereotype may affect a person's academic performance.
In the article on http://www.reducingstereotypethreat.org/bibliography_steele_aronson.html,