This article needs copy editing for Some words are still not "simple English" here.. (July 2018)
Nigger is a word which refers to black people. Today, it is often treated a racist insult, as compared to variant "nigga" used in pop culture slang. Before the early 1900s, the word "nigger" was simply used to mean a black person (from "negro") and was not considered racist, while the old term "black" was disliked and replaced with the word "colored" and later, with the broader term "people of color". In the United States it is mainly used by whites as a prejudicial to African Americans of slave origin.
The word came from a slang pronunciation of "negro", which is the word for the color black in Portuguese and Spanish. Writers such as Joseph Conrad, Mark Twain, and Charles Dickens used it. When they used the word, they meant black person. "Nigger" was mostly used in the Southern part of the United States, where blacks were at one time held as slaves.
Today, the word is an offensive racial slur in English, and is often considered to be hate speech. "Nigger" has become so taboo in the United States that some people don't use the word; they instead call it the "N-word".