The United States has always been a country of immigrants and one in which it is common for citizens to move within its borders.
It means many people can identify with Mr Obama's connections to numerous places and countries.
His mixed background led conspiracy theorists to suggest he was not a natural-born US citizen, and, under the US constitution, not eligible to be President.
But Mr Obama published his full birth certificate in recent weeks, proving he was born in US.
Barack Hussein Obama was born on August 4, 1961, in Honolulu in Hawaii. His father was also called Barack Hussein Obama and his mother, Ann Dunham, came from Wichita in the US state of Kansas.
Mr Obama's father originally came from a place called Nyang'ma Kogelo in Kenya, and he met Ms Dunham while the pair were studying at the University of Hawaii.
Ms Dunham's ancestors came from Europe -- England, Wales and, as we all know, from Moneygall in Co Offaly.
They married in February 1961, but divorced after Mr Obama senior went to study in Harvard University in Massachusetts.
He later returned to Kenya and died in car crash in 1982, having married three different women, and fathering six sons and a daughter. After leaving Hawaii, he only came back to the island to visit his son Barack once, in 1971.
Did President Obama spend his entire childhood in Hawaii?
No. After divorcing Mr Obama's father, Ann Dunham married Lolo Soetoro, an Indonesian student in Hawaii, in 1964.
But Mr Soetoro's visa to allow him study in the US was revoked by the authorities in 1966 because of political unrest in Indonesia, and he had to return to his home country.
Ms Dunham and Barack Obama followed to him to Indonesia a year later and, as a small boy, the President attended local schools in the Indonesian capital of Jakarta.
But his mother sent him back to Hawaii in 1971 and he lived with his grandparents, Madelyn and Stanley Armour Dunham. He graduated from high school -- like secondary school -- in Hawaii in 1979. His mother returned to Hawaii in 1972, but went back to Indonesia in 1977. She again returned to Hawaii in 1994, before dying of cancer a year later.
What did President Obama do after finishing high school in Hawaii?
He first went to college in Los Angeles between 1979 and 1981, when he transferred to Columbia University in New York City. During this time, he also went to Indonesia to visit his mother and sister Maya, who was born to Ms Dunham and Mr Soetoro in 1970.
His studies in New York focussed on political science and international relations and he graduated from Columbia in 1983. He stayed in New York for another two years, working in a number of different jobs.
But I thought Chicago was his hometown, not New York?
That's right. After his years in New York, he moved to Chicago and took up a job as a community organiser on the city's traditionally poor south side. He stayed in the job until 1988, the year in which he also travelled to Kenya to meet his relatives on his father's side for the first time.
After his visit to Kenya, he entered the prestigious Harvard Law School and graduated in 199. During his summers at Harvard, he returned to Chicago to work in some of the city's law firms. In the summer of 1989, he met his wife to be, Michelle Robinson, with whom he would have two daughters, Sasha and Malia.
From his graduation from Harvard until his election to the White House, Mr Obama and his family lived in Chicago.