Calling someone "black" isn't racist. That would mean callin someone "white" or "brown" is racist too. My African friends call themselves black ...
Calling yourself black, white or brown, (so i've heard) isn't racist, but calling someone else is. Though in some situations, it is acceptable.
In depends on context and culture. I'm sure you live somewhere different to me. Where I am, calling someone else "black" who is actually African isn't offensive.
Here, some people get offended by being called black by a white and others dont, so it's hard to tell around here. Of course, around here, there are mainly black gangs, weapons included, so that might be a reason to be offended.
Ohh ok. Well I guess in the case of that area, people have to be careful.