What is racism?

This is in response to a screed about racism being one-sided.  Racism as white on black only when the name calling seems to go both ways.  But racism is more than name calling and not recognizing that is really the heart of racism:

If you don't know why you are a racist, then anything I say to you will fall on deaf ears.  People are cruel---some are more cruel than others because they think calling people names is just fine (explained away because other people call them names).  But this country was founded by slave owners who tried to carry slavery over past the emancipation proclamation.  Racism became denying them rights that everyone else had including eating in the same places, drinking from the same fountains, voting, marrying who they wanted to marry and being lumped all together under some of the most demeaning names possible.  I dislike these these screeds written as if it's alright for them to call people names because people call them names.  BS, period.  Name calling is childish and uncalled for no matter who is doing it.   But in America a racist is more than just someone who calls people of other ethnic groups names---racists are people who declare that "those people"  are in some way inferior and act that way.