What it is
Martin Luther King Jr. Day honors the civil rights leader, who was born on January 15, 1929. Because the holiday is always the third Monday in January, it falls between January 15 and January 21 and sometimes lands on his actual birthday.
Congress has also designated it a national day of service, and many people spend it volunteering.
Is it a day off?
Federal and state government offices, banks, schools and the stock market close. Private employers are split: many large companies give the day off, but it is less common than the "big six" holidays such as Thanksgiving and Christmas.
History
President Ronald Reagan signed the holiday into law in 1983, and it was first observed nationally in 1986. It took until 2000 for every state to recognize it under that name.