Donald Trump mimicked Barack Obama as he left the White House to be inaugurated 45th president of the United States.
Walking side-by-side, the pair greeted senior Democrats and Republicans and journalists before they made their way to Capitol Hill.
The outgoing President waved and said clearly to the cameras: “Hello everybody.”
Mr Trump followed Mr Obama by repeating the same phrase.
Follow live updates from in inauguration here.
The exchange sparked a reaction on Twitter, with one person joking: “If we're lucky, he'll just do that for 4 years.”
Another wrote: “Imitation is the highest form of flattery.”
Minutes later, Mr Trump gave a thumbs-up, pumped his fist and mouthed "thank you" as he walked to his seat on the steps of the Capitol, next to incoming Vice President Mike Pence.
Ahead of the swearing-in ceremony, Mr Trump and his wife Melania were greeted at the White House by President Obama and Michelle Obama for the traditional private meeting of outgoing and incoming presidents and their spouses.
Posing for photos on the North Portico, the couples exchanged hugs.
After taking the oath, Mr Trump will go to a celebratory lunch with lawmakers and parade up Pennsylvania Avenue, passing his newly opened Washington hotel.
Meanwhile, workers at the White House will begin to move out the Obamas and prepare for its new occupants.
Moving trucks were on standby on Friday morning at the White House.
Mr Obama will continue to live in Washington but will first go to California with his family for a holiday in Palm Springs.
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