I really can't stand it when well-meaning people (usually liberals*) pooh-pooh racism by saying something along the lines of "I just can't understand how anyone can hate someone just because of the color of their skin." Don't get me wrong, I'm all for pooh-pooing racism, and yes, I don't understand how anyone can hate someone just because of the color of their skin. The problem is that that's not why anyone hates anyone. And when dealing with something as insidious and as important as racism, I think it's important to understand what's going on and to be scrupulously accurate.
Skin color is not what active racists** hate. It's simply the most obvious external indicator of what they hate, which, it seems to me, is really genealogy (not the concept of genealogy, but the genealogy of the targets of their hatred). Two examples from still-recent history (and, to a less visible extent, the present) should explain why I say that.
First, a hundred years ago, if you were, say, Irish or Italian, you weren't considered a member of the group called "white". This despite the fact that Irish and Italian skin tones don't tend to be all that different from those of the peoples who were considered "white" (and, in the case of the Irish, tend to be whiter).
Second, consider the phenomenon of "passing", where Black people with light enough skin attempted, often with success, to pass themselves off as white. Obviously, the presence of light skin color here complicates the issue, but think--if it was the skin color that people hated, it wouldn't have mattered if the people passing were revealed; there would be no "really Black" to worry about. They'd just be white. What these people were (and probably some still are) hiding is that they have members of their family tree who came from somewhere other than a few approved countries in Europe during the period of recorded history.
And that, right there, is the hatred-target of active racists: a genealogy that includes people from outside of certain specific European countries.
I'm not sure that I'm done with this thought. As usual, I'll say that there may or may not be more to come.
*Who in most, more sensible, countries are rightly considered to subscribe to a center-right ideology. It's only in wacky America that they're bizarrely considered to be anywhere on the left, let alone the far left.
**I specify active racists because we are all at best passive racists. Because in this society it's impossible to avoid both being influenced by one's own unconscious prejudice and taking one's place in the heirarchy of racial privilege. This is another reason I dislike the sentiment I'm discussing here--because reducing racism to "hatred" obscures a great deal of what racism actually is.