Xenophobia is a fear of foreign people. People who live in the US may mean a fear of themselves since most of these people are descended from immigrants who came to their country to find a better life. Sometimes xenophobes treat people as foreigners even when the families of those imagined to be foreign lived in the country for generations. More frequently the targets of xenophobia are relatively recent immigrants. Xenophobia can cause riots and pogroms. In the worst cases it causes Genocide. Although it differs slightly from racism, people who are xenophobic tend also to be racist.