On Monday morning, U.S. President Barack Obama was publicly sworn in during a ceremony in front of the U.S. Capitol, to herald the start of his second term.
After the swearing-in, Obama delivered his Inaugural Address, which will be followed by numerous festivities, including the Inauguration Parade. (Here is a complete list of today's events.)
Today's oaths are ceremonial - President Obama and Vice President Joe Biden took their official oaths of office for their second terms in two, separate private ceremonies on Sunday.
The inauguration ceremonies and related events Monday will be open to members of the public, with about 800,000 anticipated in the country's capital for the festivities.
Chief Justice John Roberts administered the oath of office to Obama in the Blue Room of the White House, with the aid of a Bible that belonged to First Lady Michelle Obama’s paternal grandparents.
Supreme Court Justice Sonya Sotomayor administered the oath of office to Biden at the vice president's U.S. Naval Observatory Residence in Washington, with the assistance of the Biden family Bible.
Both the president and the vice president began their Sunday by participating in a wreath-laying ceremony at the Tomb of the Unknowns at the Arlington National Cemetery in Virginia.
And the nation's leaders for the next four years ended it by attending an inaugural reception at the National Building Museum in Washington.
Below are a few of the many images captured of the country's first and second families during the inaugural events.
President Barack Obama is seen here delivering his second inaugural address. Reuters
U.S. President Barack Obama recites his oath of office as first lady Michelle Obama looks on during swearing-in ceremony. Reuters
U.S. Supreme Court Chief Justice John Roberts administers the oath of office to U.S. President Barack Obama during ceremony. Reuters
U.S. President Barack Obama arrives for his swearing-in ceremonies on the West Front of the U.S. Capitol in Washington. Reuters
Crowds gather on the National Mall to witness the swearing-in ceremonies for President Barack Obama in front of the U.S Capitol. Reuters
Placemarks are set for the Obama and Biden families before the presidential inauguration on the West Front of the U.S. Capitol. Reuters
People smile as they enter the National Mall for the ceremonial swearing-in on the West front of the U.S. Capitol in Washington, D.C. Reuters
Christine Boyd cheers as she watches U.S. President Barack Obama take his second-term official oath of office in Washington on Sunday afternoon. Reuters
A vendor sells U.S. flags with President Barack Obama pictured on them in Washington on Sunday afternoon. Reuters
Katy Perry performs under a photograph of U.S. President Barack Obama at the Kids' Inaugural Concert in Washington on Saturday night. Reuters
Guests arrive for the inauguration ceremony of U.S. President-elect Barack Obama as the 44th President of the United States, in Washington, January 20, 2009. Reuters
U.S. President Barack Obama, first lady Michelle Obama, Vice President Joe Biden, and second lady Jill Biden attend an inaugural reception at the National Building Museum in Washington on Sunday night. Both the president and the vice president took their second-term official oaths of office earlier in the day. Reuters
U.S President Barack Obama takes his second-term official oath of office from U.S. Chief Justice John Roberts as first lady Michelle Obama holds a Christian Bible and the Obamas' daughters Malia and Sasha look on in the Blue Room of the White House in Washington on Sunday afternoon. Reuters
U.S. President Barack Obama walks with his daughters Malia and Sasha after taking his second-term official oath of office in Washington on Sunday afternoon. Reuters
Members of the U.S. Army's Old Guard Fife and Drum Corps perform before President Barack Obama speaks at an inaugural reception at the National Building Museum in Washington on Sunday night. Reuters
Supporters listen to U.S. President Barack Obama speak at an inaugural reception at the National Building Museum in Washington on Sunday night. Reuters