The first Latin American pope was born in Argentina, the son of an Italian railway worker.
Jorge Mario Bergoglio and his four siblings grew up in Buenos Aires.
While a teenager, he had an infection that damaged his lungs.
After studying chemistry, he went to seminary and became a Jesuit priest when he was 32.
National Catholic reporter Father Thomas Reese says, as Bergoglio rose through the ranks of the church in Argentina, he maintained a simple lifestyle.
"He takes his vow of poverty very seriously.
He refused to live in the bishop's palace, he moved to a very simple apartment, cooked his own meals and he didn't want the chauffeur-driven limousine that the bishop normally had,” Reese said.
As a Cardinal in Argentina, he sparked controversy when he chastised priests for refusing to baptize the children of single mothers.
But he was criticized for not speaking out against his country's military dictatorship in the 1970s and 1980s.
Pope Francis is also known for his compassion for the poor.
As a priest, he reportedly once gave all the money in his wallet to help a homeless family who wrote to him.
Vatican spokesman Thomas Rosica says, just before being elected pope, Cardinal Bergoglio entered the conclave with a sense of apprehension.
"I saw him at different functions these past years, but Sunday night we went for a walk here.
So as we left, we parted, I said, 'Padre, are you nervous?' and he said, 'Yes, please pray for me.'
But he said it with such emotion, so I was very happy,” Rosica said.
His fellow cardinals say the 76-year-old Jesuit is kind and funny and that, as Pope Francis, he will most likely maintain his humility and emphasize service to the poor.
He felt inferior to his older sibling.
Are you sure there is no danger of infection now?
I was baptized a Catholic.
I had compassion for him.
What is his function on the committee?