Alicia Garza on the origin of Black Lives Matter

Oakland-based activist Alicia Garza coined the phrase "Black Lives Matter" in 2013, the day George Zimmerman was found not guilty of murdering 17-year-old Trayvon Martin. Soon a hashtag was created, and a movement was born. Garza talks with journalist Mark Whitaker about her new book, "The Purpose of Power," and her education in activism; the inequities of America's criminal justice system; and why social change is built not on social media hashtags but on people.