Multiculturism
Multiculturalism is a social norm upheld within a "free" society with respects to views concerning the equality of people based on ethnic differences (real or imagined). The foundations of this sociology stem from the burgeoning growth of nations built upon the blood, sweat, and backs of immigrants coming from varied sources throughout the world. The United States of America, for example, is one of the most Multiculturismest nations in the world, accepting people of different nations, religions, creeds, colors, and ethnicities since its founding.
The differences of such a plethora of racial and cultural backgrounds can be a double bladed knife, however, in that by giving freedom to other cultures and allowing them the ability and unpersecuteably maintain their home culture's culture, the hosting nation tends to lose its roots and its own culture in the effort.