Discrimination based on Race, Religion or National Origion is clearly defined in the United States. Discrimination based on Race = Racism, Religion = Religionism, National Origion = Nationalism. They are not the same, and can overlap. All three are commonly used classifications of people, and in many ways, helpful for understanding a person's history, culture, values and traits. However, they are not a good basis for discrimination when considering items of public interest. I think when we talk about racism, in the narrowest terms, we are talking about discrimination based on race. Is this thread talking about general discrimination, or just race and racism?
Note: Language has commonly been a valid and proper way to discriminate because of the necessity to communicate in a normal social order. Some of the issues with Language have already been brought up. Without a common language, the normal social and cultural order breaks down, and leads to natural divisions. Canada and some Balken states have tried to overcome this natural barrier, but it has been a difficult obstacle to National order and unity. Racism is when a person is discriminated against even though they have learned and can speak/write another's language. Someone from Switzerland should pipe in on this issue.