Today, Monday 16th January, it's a special day in the USA. It is "Martin Luther King Day" (or King Day or MLK Day) and this is a federal holiday. It is celebrated annually on the 3rd Monday of January to commemorate the birthday of American civil rights leader Reverend Dr. Martin Luther King, Jr (15th January 1929).
Martin Luther King was hugely influential in the American Civil Rights Movement (despite never holding public office) and was a major advocate of non-violent activism in the struggle for the end of racial discrimination under US law. He was assassinated in 1968.
