What does 'black' mean?

Can someone tell me what the term 'black' means. Is this an anthropological term? If so, what does it mean anthropologically?

Obama, who, up to this point, is my most written-about subject, is called America's first black president. Using information from Wikipedia's main entry on Obama; his mother was of mainly English descent, which presumably would mean she was Caucasoid (I'm using anthropology terms here), and his father was Kenyan, which presumably means he was Negroid. Now keep in mind ethnic origin does not at all guarantee racial origin so if anyone has further information about the racial origin of Obama's parents please speak up. (Obama apparently writes a lot about race in his books so if you have copies of any, you could help out here.)

So in today's vernacular, using the above assumptions, Obama is half white. So why is he referred to as 'black'. Wouldn't a more apt description be mixed race or half black and half white?

Another perplexing example is Tiger Woods. He is often referred to as black. In the words of Wikipedia he is 'one-quarter Chinese, one-quarter Thai, one-quarter African American, one-eighth Native American, and one-eighth Dutch'. Again, ethnic origin does not guaratee racial origin so if you have any further racial info about Tiger, please speak up. But using his ethnic origins as a basis, his racial makeup is presumably five-eighth's Mongoloid (that's the Thai, Chinese, and Native American), one-quarter Negroid (African American), and one-eighth Caucasoid (Dutch).

Or in other words, Tiger is one-quarter black. So why do some people call him 'black'.

I believe the currently accepted word for Mongoloid is 'brown'. Since he has more than twice as much brown in him than any other race, why don't people call him 'brown'? Personally I prefer not to call people any colour. To me, Tiger is just Tiger, and he's AWESOME!! But his awesomeness is a topic for another day.

Tiger's wife is Swedish and she certainly appears to be mostly Caucasoid. If so, this would make Tiger's kids one-eighth black. I'm wondering if anyone will refer to them as 'black'.

Why do I care about this? I look forward to the day that a person's colour, that is, their race, is irrelevant, period. We are getting there. I hear less and less references to Tiger being black. He's just Tiger, one of the most amazing people on the planet. And to his credit, I think he has had a hand in that. He never seems to grind the axe on race and it's good on him. Instead he puts his money where is mouth is with the Tiger Woods Foundation and helps countless underpriviledged kids . . . of all races.

Now, ethnicity is fine. I'm proud of my ethnic background as most people are. And the richness of ethnic cultures around the world justs adds to our collective charm. But race? It has no place.

Race has no place. That's my motto for the day.

Cheers.