The Cold War began after World War 2 and lasted from 1945-1991. It involved geopolitical tensions between the Soviet Union and the United States. Key events included the formation of opposing military alliances like NATO and the Warsaw Pact, the Berlin Blockade, the Cuban Missile Crisis, and a nuclear arms race. Important leaders during this time included Nikita Khrushchev, John F. Kennedy, Ronald Reagan, and Mikhail Gorbachev, whose reforms helped bring an end to the Cold War.