What is racism??

To understand better what racism really is, I saw the film CRASH by Paul Haggis. Even not going to Poland, I understand better what racism means, by watching the movie. Somethimes the film was hard to look at, but the reality is there. The movie shows us that there is not only a conflict between white and coloured people,but also between coloured people themselves. Many people are afraid when they are in the neighbourhood of people of another race. They have a presumption. For example, there is a moment in the film that a black boy wants to show the policeman, that he's from the same religion as him. The policeman was afraid and thought that the black boy took his gun out of his pocket. So he shot the black boy.