Beyond mere racism (a pre-programmed aversion to the Other), racialism takes
racism into the realm of worldview. In the 20th century, it's a reaction to
the "melting pot" or "cultural mosaic" brought about by slavery,
colonialism, and immigration. Often linked with violence (or threats of
it), e.g. the Ku Klux Klan, neo-Nazis, "Christian Identity" groups, but some have tried to go the electoral route - e.g. Britain's National Party, an offshoot of the National Front.