A religious movement originating in the 1930s in the USA. Black Islam (also known as Farrakhanism for its current leader or Nation of Islam) was founded by Wallace Fard Muhammad in response to whites' racism. It is not true Islam, and takes its beliefs from Christianity and Islam and Elijah's personal beliefs (not to be unfair, but it's true). It holds that the Bible and the Qu'ran are equal in authority and teaches that blacks must do anything to get back at the white man for revenge. It gained a pretty large following, but I think membership has declined since its birth, I'm not too sure. Some members were quite active in politics, e.g. Malcolm X (he changed his name from his "slave name" Malcolm Little). However, after Malcolm was true to his faith and took his hajj to Mecca, he came back a changed man. There he had learned true Islam and converted to Muhammad's (pbuh) preached religion, as well as bringing Muhammad Ali} with him. Malcolm X changed his name to El-Hajj Malik Al-Shabazz and quit the Nation of Islam, for which he was later assassinated, some believe (the assassination; he definitely became a Sunni Muslim).
Anyway, one of Wallace's disciples, Elijah Poole (who later became Elijah Muhammad) started to preach that Wallace Fard was the Messiah, and God in person form (like Christians' view of Jesus).
If there are any Black Muslims out there reading this, feel free to correct me or add anything.
Black Islam is a religious as well as socio-political organization to improve the welfare of African Americans. It has been called sexist, homophobic, and racist, but also has been praised as helpful to black businesses and for improving inner city neighborhoods.