There is some debate amongst experts as to what race "Moor" refers to in Othello; however, the most common interpretation is that Othello was black and most likely of African descent. Othello's "blackness" is referred to several times in the play, and Shakespeare was no stranger to Christian Negroes.
The reason experts struggle to assume Othello was black is because of the ambiguity of the word "Moor" during Shakespeare's time. "Moor" in original Greek simply means black. However, it was not uncommon for people during Shakespeare's time to refer to someone who was simply darker in complexion as black. Also, according to SparkNotes, the word "Moor" today refers to Islamic Arabic people who moved from Northern Africa to Spain during the eighth century.
There are some who interpret "Moor" as a Spanish Moor. Ben Arogundade shares author Peter Ackroyd's theory of Othello as a Spanish Moor based on historical context. Ackroyd argues that Shakespeare would have made Othello a Spanish Moor because he knew a lot about Spanish politics. Moreover, Shakespeare is known for pillaging his stories, and there was a Spanish King, Phillip II, who was of jealous nature and accused of strangling his wife in bed. This type of story would have been attractive inspiration to playwright William Shakespeare.
Nonetheless, there is still strong support from in-text descriptions that lead most people to believe Othello was a black Moor of African descent. Shakespeare's intent may never be certain, and the play has been successfully performed for hundreds of years, sometimes with Othello cast as a black man and sometimes with Othello cast as Arab.