Prejudice means to pre-judge something by assuming you know all of the facts and information about it – before you really do. Prejudice can be a huge problem for successful communication across cultural barriers. The term ‘prejudice’ is almost always used in a negative way to describe the behavior of somebody who has pre-judged others unfairly, but pre-judging others is not necessarily always a bad thing. Many of us lead busy lives and we cannot be expected to get to know everybody who we interact with. However, in Western Cultures, judging others by their skin color, social class, gender, age, religion, etc, has become completely unacceptable - and in many cases a criminal act. Many Western institutions, including, governments, universities and large businesses have developed very strict policies about what you can and cannot say to others.
Racism comes from prejudices based within the idea that some races are superior or inferior to others due to biological differences - although some would argue that race is entirely a social construct. Racism leads to discrimination, of which, there are countless terrible examples throughout history. Racism can be found in actions, behaviors and language both intentional and unintentional. 'Institutional Racism', is a vague, unproven, yet, popular theory that Racism is part of the institutional systems that societies rely on, the police being a good example.
Xenophobia means fear of strangers or of the unknown. The term is usually used to describe fear or dislike of foreigners. Xenophobia, is mostly cultural and aimed at customs and behaviors from outside which are considered alien. However, it is also often based in racial prejudice as well.
Within societies Xenophibia can often lead to exclusion, mistrust and sometimes violence which is often aimed at the most recently arrived immigrant populations.
Another form of xenophobia can be seen when national governments or powerful political groups use propaganda through the media to purposefully demonize certain foreign countries in order to gain support for themselves. This is particular prevalent in wartime but if you look carefully at the media around the world today it isn't too difficult to find examples of this happening regularly.
Xenophobia is closely linked to extreme Nationalism.
Sexism and Gender
The word sexism is usually used to describe prejudiced behavior by a man towards a woman, but technically can be used the other way round as well. Misogyny, is a term used to describe a man who dislikes or is prejudiced towards women. There is a very vigorous debate within Western Cultures about the prevalence of misogyny in society. There is also debate around the issues of Lesbian, Gay, Bisexual and Transgender (LGBT) rights. These debates can be extremely emotional and polarizing.
Traditional gender roles can be very different in different societies which unsurprisingly can lead to disagreement and conflict when one or both sides refuse to compromise their deeply held beliefs.
Within most cultures it is probably fair to say that men have enjoyed a higher social status and more personal freedoms than women throughout history. It is also probably true that much of the difference found between genders is learned through culture rather than inherent in biology - but maybe not as much as some would like us to believe!
Classism is discrimination based on social status and wealth. It has been associated with Social Darwinism which is basically the belief that those who enjoy the advantages of high status deserve their rich rewards because they are more highly evolved than those that live in poverty. In this way it can be viewed in a similar way to racism. Classism can be found in language (with regional accents a key indicator of lower class), education, social activities, social preferences (eg, taste in music, and entertainment), location of home, amount of money possessed among many other indicators.