The blood type of B negative is also uncommon, occurring in "2% of Caucasian, 1% of African American, 0.4% of Asian and 1% of Latino American" populations, according to the American Red Cross.

If you don't know your blood type, you're not alone. However it is important medical information to know, and here's how you can find it.

are people with O-negative and B-negative blood. People with Type O are valued as universal donors who can give blood to anybody, while those with a negative RH are especially valuable because they ...