I've never understood the concept of calling someone who's black "African-American" when they in fact were not born in Africa and immigrated to America. When you immigrate from another country to America, you become (your country of origin's ethnicity) - American. Your ancestors could have immigrated from Africa, but by lineage that doesn't make you African-American. My ancestors (my great grandmother) immigrated from Ireland to America. She was Irish-American, I am not. My lineage is, but I was not born in Ireland.
I don't per-say understand the offense some people take when you refer to them as black. It's not racist to call someone who is black, black. Just like it's not racist to call someone who's white, white and not "Caucasian".
If you're using it in an offensive way by the tone of voice you use when saying it or in connection with an offense phrase that's different, that's obviously meant to be offensive and you should of course take offense. But if someone just refers to the color of your skin as black in a general situation, that shouldn't be offensive. It's all personal experience of course, this is just my take on it.
really you're in no place to tell someone what is racist and what isnt racist
if theyre offended theyre offended regardless
also the irish-american comparison doesnt work because irish is little more than an ethnic identity, and a white one at that, and doesnt carry the same weight as a racial identity, especially in this country. people are free to call themselves whatever they like.
also unrelated- but i'd like to point out that the term caucasian isnt just used to refer to white people. , the peoples of north africa, the horn of africa, most of asia (excluding eastern asia) are caucasians.
using it to refer to white people is a continuation of Blumenbach and Meiner's work in trying to prove european superiority over the peoples of different regions. its fascinating and terrible terrible work that has unfortunately still got a stranglehold on us culturally.