In the United States, the so-called Jim Crow laws were made to enforce segregation, and included laws that would prevent African-Americans from doing things that a "white" person could do. For instance, Jim Crow laws regulated separate use of water fountains and separate seating sections on buses. Jim Crow laws varied between communities and states.
The modern civil rights movement is often considered to have begun in an act of civil disobedience against the Jim Crow laws when Rosa Parks, a black woman, refused to give up her seat on a bus to a white man.
The origin of the name Jim Crow is disputed by some, but it seems most likely to come from the title character in a minstrel song (possibly written in 1832) and popular from the mid-nineteenth century to the turn of the twentieth century.