Um... according to just about everyone I've heard, including and especially people on Tumblr, people from Spain are white as hell.
Do I have to point the anthropological inaccuracy of that statement for you?
Is "white" a well-defined anthropological concept?
Actually asking. I'm never sure who does or does not count as white.
Not really? There are many nations like Italy, Greece, and Spain that are arguably predominately "white" but have darker than average skin tone due to the climate. Common American-style racism against darker skinned ethnicities has never stopped groups that many would call totally white from being terribly racist against one another. Everyone here could probably tell you about what the Irish (and other immigrants to a lesser extent) went through 100+ years ago, but fewer would describe the opinions various European countries tend to have about other European countries.
The best way to identify the various races is generally morphology rather than mere skin tone. People of African, Asian, and Caucasian descent all have different enough bone structures that anthropologists can roughly identify the race of a skeleton. I say "roughly" because race differences are an inexact thing on their own, so any scientific attempt to say what race someone was by their bone structure can only say "This is likely what they were." It gets more complex with places like South and Central America; despite the common perception of Hispanic and Latino peoples as being dark-skinned and dark-haired (as the modern ethnicities are derived from mixing between Europeans, Native Americans, and African slaves), there's many who are indistinguishable from a Barbie doll.
And obviously the US-centric definition of racism popular on the internet doesn't really mesh well with reality outside of specific areas of the world and periods in history.