Barack Obama has been inaugurated for his second term as president of the United States.
Obama was sworn into office on January 21 on the steps of the U.S. Capitol in Washington, D.C.
The public ceremony came a day after he took the official oath of office in a private White House ceremony, in accordance with the U.S. Constitution, which says a presidential term ends at noon on January 20.
In his inaugural address, Obama called on a divided America to join as one nation and one people.
"Each time we gather to inaugurate a president, we bear witness to the enduring strength of our constitution. We affirm the promise of our democracy. We recall that what binds this nation together is not the colors of our skin or the tenets of our faith or the origins of our names," Obama said.
"What makes us exceptional -- what makes us American -- is our allegiance to an idea, articulated in a declaration made more than two centuries ago: 'We hold these truths to be self-evident, that all men are created equal.'"
Obama vowed to renew "strong alliances" around the world, saying the United States was committed to finding security without "perpetual war." He also said Washington will support global democracy, acting on behalf of those who long for freedom.
"This generation of Americans has been tested by crises that steeled our resolve and proved our resilience. A decade of war is now ending. An economic recovery has begun," Obama said.
"America's possibilities are limitless, for we possess all the qualities that this world without boundaries demands: youth and drive; diversity and openness; an endless capacity for risk and a gift for reinvention," he continued.
"My fellow Americans, we are made for this moment, and we will seize it -- so long as we seize it together. "
Brian Balogh, a history professor at the University of Virginia, said Obama’s inaugural address was “a defining moment” for the president because he used it to explain the ideological and philosophical ideas that motivate him.
"I thought this was a bold speech because the president laid out a fundamental rationale for all of these programs he proposed," Balogh said. "And that rationale is, ‘America is stronger when it acts collectively.' To even say the word ‘collective' is dangerous in American history because it conjures up images of communism, of socialism. At a minimum, it comes dangerously close to using the 'L' word – liberalism.”
Hundreds of thousands of people filled the National Mall to witness the inauguration.
Former Presidents Jimmy Carter and Bill Clinton attended the ceremony along with members of Congress and other dignitaries.
Vice President Joe Biden also publicly took the oath of office before Obama.
Myrlie Evers-Williams, the 79-year-old widow of slain civil rights leader Medgar Evers, delivered the invocation, becoming the first woman and nonclergy member to do so.
The ceremony was held under tight security.
With reporting by AP and AFP