Nobel Prize founder Alfred Nobel left vague instructions on how to select winners of the peace prize, but the committee typically selects candidates who have been involved in peace or democracy work for many years.
Below are examples of winners who were honored for efforts, and events, in the months leading up to the announcement.
2009: President Barack Obama for efforts to strengthen international diplomacy and cooperation between peoples, especially his calls for a world free of nuclear weapons after taking office in January.
2000: South Korean President Kim Dae-jung for democracy and human rights work as well as for seeking reconciliation with North Korea. Earlier that year, Dae-jung made the first visit to Pyongyang by a South Korean president.
1998: Irish Catholic leader John Hume and British Protestant leader David Trimble for their leading roles in negotiations that produced Northern Ireland's Good Friday peace accord that year.
1994: Palestinian President Yasser Arafat and Israeli Foreign Minister Shimon Peres and Prime Minister Yitzhak Rabin for achieving the Oslo peace accords in 1993 and toiling to enact their goals.
1990: Soviet leader Mikhail Gorbachev for leading efforts to promote peace between the East and the West, an award given as the Soviet empire was crumbling.
1978: Egyptian President Anwar al-Sadat and Israeli Prime Minister Menachem Begin for Middle East peace efforts, specifically the Camp David peace accords signed on Sept. 17 that year.