How do stereotypes create prejudice or even discrimination in today’s society?

I saw someone post this question and i would love to address that…

“to be prejudice is to have a negative attitude that is held toward members of a group…
like other attitudes it has three components:
belief: all indians are alcoholics, muslims are terrorist, african americans are gangsters
emotions: i hate jews, i loathe asians, i despise iraqis
behavorial dispositions: i would never hire a mexican, i would never sit with an african american, if my kid was a lesbian, i would kill her.

prejudices are not limited to racial groups. women, homosexuals, the aged, the disabled, and the mentally ill are also targets for prejudices. even cliques at schools are targets too. thus many people hold prejudicial attitudes toward one group or another, and many have been victims of prejudice.

prejudice may lead to discrimination, which involves behaving differently, usually unfairly, toward members of a group.”

processes that promote prejudices…
where do we get most of our stereotypes from?
if you think about it for a sec, you will realize that almost everyone in the US has a television.
and so almost everyone watches it.
theres so much, these days, about how muslims are terrorists and about how muslims are commanded to kill the “infidel”, so i believe we get most of our stereotypes from the media.

why is stereotyping so easy to promote?
i have two reasons…
the media takes advantage of the fact that people are ignorant…
they have no prior knowledge of the subject… they won’t know if it’s right or wrong…
some people are like sheep and believe what the media tells them… 
so the people in the media say, “lets give them the knowledge, and they will believe anythin we say. they wont know if it’s right or wrong.”
this is the most obvious way of the promoting the stereotypes of islam.

and one of the reasons is fear…
when people are afraid of something, they tend to keep away from it.
my impression is that racist people are afraid that african americans will rob them.
people are afraid to admit that they are gays because they are afraid to be hated on by their family and friends and society.
people are afraid to admit that they are ocd or schizophernic because of the stigma that the mentally ill have…
people are afraid to be identified as muslim because of the stigma that the muslims have

“according to the social identity perceptive, self esteem depends on both personal and social identity. social identity refers to the pride derive from membership in various groups. the theory purposes that self esteem can be undermined by either threat to personal identity or social identity. threats to both personal and social identity may motivate efforts to restore self esteem, but threats to social identity are more likely to provoke responses that promotes prejudices and discrimination. when social identity is threatened, individuals may react in two ways to bolster it. one common  response is to show ingroup favoritism, for example, tapping an ingroup member for a job opening, or rating the performance of an ingroup member higher than that of an outgroup member. a second common reaction is to engage in outgroup derogation, in other words, to “trash” outgroup that are perceived as threatening. outgroup derogation is more likely when people identify especially strongly with the threatened ingroup. when people degorate an outgroup, they tend to feel superior as a result, and this feeling helps to affirm self worth. these unfortunate reactions are not inevitable, but threats to social identity represent yet another dynamic process that can foster prejudice.”

note: the first part and the last part is from my psych book, the middle part is from me.