The Civil Rights Movement was a mass movement whose purpose was to win civil rights for African Americans. While there were whites in the movement, the overwhelming majority of activists were African Americans.
The goal of the movement was to gain equal rights for African Americans. The movement was pushing for an end to segregation and legal discrimination. It was also trying to win the right to vote (which African Americans legally had already but which was blocked in a number of ways in the South).
The movement is often said to have started in 1955 with the Montgomery bus boycott. The successful stage of the movement ended in 1965 with the passage of the Voting Rights Act. The best-known leader of the movement was Martin Luther King, Jr.