Define racism!

[Koga No Goshi]

A thousand definitions. Most people just go off their own personal one.

I use the academic one I studied and operated off in college. Racism is the advocacy, implementation of, or justification of, systems of inequality and use of power which advantages a favored group and disadvantages others, formally or informally (i.e. through courts and laws or just by default through prejudicial practices by everyday people).

In other words, it has a power component backing it up, or you propose that power (laws, government, punishment for crimes, access to jobs, whatever) should uphold your particular racist views.

Racism just in the sense of "I don't like black people, I think they're stupid" is bigotry and prejudice, and a racist mindset and attitude. But when people break racism down to just being that, they're overlooking the much more important factor of institutionalized (either hidden, or obvious) racism, wielding power to advantage and disadvantage on the basis of race over a whole society, rather than just individually. Slavery was institutionalized racism. The Holocaust was institutionalized racism. These things dwarf "I don't like black people."

Among colonial powers, it being very typical for indigenous people not to be able to testify in court against colonials would be a great example of this, as would apartheid and such. To a lesser extent (but still valid) would be things like harsher legal punishments or substantially higher conviction rates of one race for the same crime as another race.