Every year we honor the legacy of Martin Luther King Jr. in January. Here's everything you need to know about the holiday.

Between 1957 and his assassination on April 4, 1968, at age 39, Martin Luther King Jr. gave 2,500 speeches, wrote sermons and homilies and published five books. Meanwhile, the number of books written about King surely number in the thousands.

Martin Luther King Jr., a reverend and civil-rights activist, was assassinated at 39. However, he inspired several movements and political changes.