Nelson Mandela receives a kiss from one of his grandchildren in Pretoria in 2008.
South Africa's schoolchildren sang happy birthday to Nelson Mandela as he turned 94 on Wednesday, a day when he asks the world to honour his legacy by performing community service.
The nation's 12 million schoolchildren began their day with a special birthday song, ringing with the line: "We love you father".
"As we celebrate his birthday, we remember that he fought for us in the struggle. The struggle was to fight apartheid," said 12-year-old Kgaugelo Masunhloane at Batsogile primary school in Soweto.
"He spent 27 years in prison. We would want to say thank you Madiba, and we wish you happy birthday, and many more years to come."
Mandela, known fondly by his clan name Madiba, was unlikely to make any public appearances, but rather to spend a quiet day with his family in his village home of Qunu, where he has retired from public life.
His granddaughter Ndileka Mandela told the Sowetan newspaper that his family would celebrate with a traditional meal of tripe and samp, a corn dish popular in his region of the Eastern Cape.
"We will probably have food like samp and tripe, his favourite food," she told the paper. "The big lunch will be at 4:00 pm (1400 GMT) where we will present him with a cake."
Former US president Bill Clinton met with Mandela at his village home on Tuesday. A photograph released after the meeting showed Mandela seated in an armchair, his lap covered by a blanket, as he held Clinton's hand.
Images of the Nobel Peace Prize winner have become rare in recent years since he retired to Qunu. He was last seen in public at the closing ceremony of the 2010 World Cup in Johannesburg.
But he retains an undeniable ability to inspire, and for many South Africans remains a symbol of the best of themselves, for leading the nation away from civil war and to a non-racial democracy.
Mandela's "extraordinary life and steadfast commitment to the principles of democracy and reconciliation continues to be a beacon for people of all backgrounds who strive for dignity, justice, and freedom," said President Barack Obama and his wife Michelle.
They described his personal story as "one of unbreakable will, unwavering integrity, and abiding humility."
"By any measure," the statement read, "Nelson Mandela has changed the arc of history, transforming his country, continent, and the world."
Obama's predecessor Clinton said he was honored to have been in office as Mandela became South Africa's first black president in 1994.
"When I think about Mandela I always think about someone committed to the future," he said after leaving Mandela's home.
"We worked together as presidents and even after we left office we continued working together to improve education of the children worldwide in order for them to share the future," he added.
Tiger Woods, the first black player to win a major golf title with a record-shattering 1997 Masters victory, remembered his first meeting with the ever-charismatic Mandela.
"He has such a presence and aura about him, unlike anyone I've ever met," Woods said Tuesday at the British Open. "He has meant so much to so many people around the world, not just in South Africa."
At the Tour de France, children will unfurl a banner to wish the icon happy birthday at the start of the stage in the southwestern town of Pau.
And the science world added an unusual tribute, naming a prehistoric woodpecker after the Nobel Peace Prize winner -- the oldest type ever found in Africa.