Who
Barack Obama is the 44th President of the United States. He was elected in November 2008, 12 days before the nominations for the Nobel Peace Prize. He is the fourth US president to win the prize.
Alfred Berhnard Nobel (1801 - 1872), the man behind the peace prize, was a Swedish chemist whose best-known invention was dynamite. He owned the huge Swedish weapons company Bofors. He was also an engineer and innovator. He amassed a large amount of money and in his will he stated that it should be used to award prizes in five categories - Physics, Chemistry, Physiology or Medicine, Literature, and Peace. There is also an economics prize, but this was not one of the categories mentioned in Nobel's will.
What
Obama was awarded the Nobel Peace Prize, which is given to people who 'during the preceding year [...] shall have done the most or the best work for fraternity between nations, for the abolition or reduction of standing armies and for the holding and promotion of peace congresses', according to Nobel's will.
When