Donald Trump has been sworn in as US president, officially taking up his four-year term of office.
Mr Trump began his presidency saying that "from this day forward it's going to be only America first."
Look back at our live coverage of the inauguration here.
Transfer of power
The transition from a Democrat president to a Republican took place on the West Front of the domed US Capitol before a crowd of former presidents, dignitaries and hundreds of thousands of people on the grounds of the National Mall.
The Capitol was teeming with dignitaries for the swearing-in ceremony, including former President Bill Clinton, his wife Hillary Clinton who was defeated by Mr Trump in the 8 November election, and former presidents George W. Bush and Jimmy Carter.
As scattered protests erupted elsewhere in Washington, Mr Trump raised his right hand and put his left on the Bible used by Abraham Lincoln and repeated a 35-word oath of office from the US Constitution, with Chief Justice John Roberts presiding.
Afterwards, he stretched his arms wide and hugged his wife, Melania, and other members of his family. Then he turned around to a podium and delivered his inaugural address.
Trump's inaugural speech
"This moment is your moment, it belongs to you," Mr Trump told a large crowd.
"We, the citizens of America, are now joined in a great national effort to rebuild our country and restore its promise for all of our people.
Mr Trump said Washington had flourished and politicians prospered but the people did not share in its wealth.
"The forgotten men and women of our country will be forgotten no longer. Everyone is listening to you now.
In a nod to his post-industrial political heartland, Mr Trump talked of shuttered "factories scattered like tombstones" across the country.
"This American carnage stops right here and stops right now.
"From this day forward its going to be only America first, America first.
"We will get our people off welfare and back to work. We will follow two simple rules, buy American and hire American.
"We will unite the civilised world against radical Islamic terrorism, which we will eradicate completely from the face of the earth.
"When you open your heart to patriotism, there is no room for prejudice."
"We must think big and dream even bigger. l will no longer accept politicians who are all talk and no action, constantly complaining, but never doing anything abut it.
"The time for empty talk is over, now arrives the hour for action. Do not allow anyone to tell you that it cannot be done."
Parade, protests
Away from the Capitol, masked activists, some carrying anarchist flags, smashed store and car windows and fought with police in riot gear who responded with tear gas and stun grenades.
Police say they have charged an unspecified number of people with rioting.
Many demonstrators were expected to participate in a "Women's March on Washington" on Saturday (Sunday NZT).
The protests played out just blocks from Pennsylvania Avenue, where Mr Trump proceeded in the traditional parade a newly sworn in president takes from the US Capitol to the White House.
President Trump and Melania Trump walking part of the way during the inaugural parade to the White House. Photo: AFP
Mr Trump's critics have been emboldened to attack his legitimacy because his win came in the Electoral College, which gives smaller states more clout in the outcome. He lost the popular vote to Mrs Clinton by about 2.9 million.
Protesters clash with police in Washington streets. Photo: AFP
His opponents also pointed to the conclusion of US intelligence agencies that Russia used hacking and other methods during the campaign to try to tilt the election in the Republican's favor.
Mr Trump has acknowledged the finding - denied by Moscow - that Russia was behind the hacking but said it did not affect the outcome of the election.
His supporters, many of them working-class whites, see him as a refreshingly anti-establishment figure who eschews political correctness.
- Reuters / BBC