In Britain, former US president Barack Obama has paid tribute to the "extraordinary generosity" shown by the late Queen to his family.
In a video tribute posted on Twitter, he described how when he first met the monarch he was struck by her similarity to one of his relatives.
He said: "The first time that I met the Queen was visiting London. She reminded me very much of my grandmother - which surprised me.
"Not just in appearance but also in manner. Very gracious, but also no nonsense.
"Wry sense of humour, she could not have been more kind or thoughtful to me and Michelle."
Later, Mrs Obama and the couple's two daughters travelled back to the UK and were invited back to Buckingham Palace for tea and to ride around the grounds in the Queen's golden carriage.
"It was the sort of generosity and consideration that left a mark in my daughters' lives that's still there," he said.
Mr Obama went on: "The Queen was an excellent listener, she had a genuine curiosity, although she was impatient to get to the point."
He also remembered an occasion when she wore a brooch that Mrs Obama had given her to a dinner at the US embassy in 2011.
"It was an example of the subtle thoughtfulness that she consistently displayed not just to us, but to everybody who she interacted with," he said.
"The combination of a sense of duty and a clear understanding of her role as a symbol for a nation and as the carrier of a certain set of values combined with a very human quality of kindness and consideration, I think that's what made her so beloved not just in Great Britain but around the world."
