Watch President Barack Obama award Medals of Freedom, the nation's highest civilian honor, to 21 recipients at the White House.
Medals of Freedom are awarded to individuals who have contributed to the security or national interests of the United States, world peace and cultural or other significant public or private endeavors.
Individuals who are receiving a Medal of Freedom in Tuesday's ceremony, attended by First Lady Michelle Obama and Vice President Joe Biden, include basketball player Kareem Abdul-Jabbar, comedian and talk-show host Ellen DeGeneres, actors Robert De Niro and Tom Hanks, mathematician and computer scientist Margaret H. Hamilton and philanthropists Bill and Melinda Gates.
"The Presidential Medal of Freedom is not just our nation's highest civilian honor - it's a tribute to the idea that all of us, no matter where we come from, have the opportunity to change this country for the better," President Obama said in a statement. "From scientists, philanthropists, and public servants to activists, athletes, and artists, these 21 individuals have helped push America forward, inspiring millions of people around the world along the way."