Who is the US President, what will Donald Trump do in his first 100 days and where will Barack Obama live now?
DONALD Trump pledged to unify America when he was sworn in as US president, while millions across the globe hold protest and dozens of politicians boycotted the event.
The tycoon-turned-politician has addressed hundreds of thousands of people gathered in Washington DC and millions watching around the world, in his first speech as the 45th president of the United States.
A massive security operation was launched ahead of the event, including a heavily guarded perimeter around the US Capitol building where Mr Trump delivered his inaugural address.
Tens of thousands of protesters were expected to take to the streets of cities around the world in opposition to Mr Trump's presidency.
He was handed the nuclear codes and briefed on firing missiles ahead of the inauguration ceremony.
Who is the President of the United States?
For the first few hours of inauguration day it was still Barack Obama, but now Donald Trump has taken the reins of the most militarily and economically powerful nation in the world.
The Republican nominee achieved one of the most improbable political victories in modern US history – despite a series of controversies that would easily have destroyed other candidacies.
At 70 years of age, he is the oldest man ever to begin work in the Oval Office.
But the real estate mogul and one-time television reality star is also a political virgin - he will be the first president never to have held elected office, served in the government or the armed forces.
Trump enters office with a 37 percent approval rating, the lowest on record, according to a CBS News poll.
What will Donald Trump do in his first 100 days?
It is highly-likely the explosive “dirty dossier” on Trump’s alleged links to Russia will rumble on until after his inauguration.
The unsubstantiated 35-page report contains deeply damaging material that could be used to blackmail the president-elect written by former British MI-6 intelligence agent Christopher Steele, 52, who fled his Surrey home soon before his identity was made public.
A furious Trump let rip at a press conference following the report's coverage, slamming it as "fake news".
He said: “Does anyone believe that story? I’m also a germaphobe, by the way. Believe me.
“I think it is a disgrace that information was let out. It is all fake news. It is phony stuff. It didn’t happen."
Once the attention is back on his presidency, the billionaire is likely to focus on the subject closest to his heart, which has always been immigration.
Trump has promised to start deporting “more than two million criminal illegal immigrants” straight away.
He has also threatened to cancel visas to any country that refuses to accept its people being returned.
So if Britain did not allow the illegal aliens back into the country, none of our citizens would be permission to enter the US.
Trump is still guaranteeing to “build a wall” on the US’s border with Mexico and to get its government to pay for it.
His End Illegal Immigration Act would also impose an automatic two-year prison sentence on anyone illegally re-entering the US after a previous deportation. America already has one of the highest prison populations in the world.
The Mexican peso went into near free-fall in chaotic trading as new of Trump’s success spread.
Where will Obama live now?
In the short term, after Trump takes the oath of office on the steps of the Capitol at noon Friday, Obama will head on vacation with his wife Michelle and two teenage daughters Malia and Sasha to Palm Springs, California.
After that?
"I have to be quiet for a while. I don't mean politically, I mean internally. I have to still myself," Obama told former close aide David Axelrod in an interview for CNN.
Former presidents rarely remain in the nation's capital after their time living and working in the city's oldest public building, but the Obamas will be staying in Washington while Sasha finishes high school.
Obama, a Hawaii native who made his start in politics in Chicago and never expressed any real love for Washington, has rented a £4.3m home in the city's upscale Kalorama neighborhood.
In the middle term, Obama has expressed a wish to work with young minorities from poor neighborhoods, where school dropouts, unemployment and incarceration rates are higher than elsewhere.
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