Perhaps you're familiar with the world stage after World War II. Germany was occupied and divided between the Allied Powers of the United States, the United Kingdom, France, and the USSR. The US, UK, and France, eventually consolidated their zones, creating a separate East and West Germany. Within West Germany, democracy and Western technologies and reparations were enjoyed. Within East Germany, an oppressive communist regime and outdated technology reigned.
However, the capital city of Berlin, located deeply within East Germany, was considered too strategic a place to be under sole Soviet control. And so Berlin was also divided into four zones for the four occupying Allied nations. Upon the consolidation of the Western Allies' zones into West Germany, the Western zones in Berlin were also consolidated to form a West and an East Berlin.
This peculiar situation meant that West Berlin stood as an 'outpost' of democracy within a 'sea of communism.' The USSR, resentful that the other Allied powers owned territory deep within the Soviet zone of East Germany, wished to force the Allies out and conquer West Berlin itself. As the Cold War, an ideological conflict largely pitting the capitalist ideals of the US against the communist ideals of the USSR, was starting, Berlin became one of the first locations where the two powers stood in conflict. However, the Cold War was characterized for its lack of direct violence, and that showed through in the Berlin conflict as well.
The USSR, in control of all railroads and the like surrounding West Berlin, blockaded the city in an attempt to force its surrender through starvation. A blockade is normally considered an act of war. However, the US was not willing to respond with violence after the just-recently finished and heavily bloody World War II. Yet, President Truman was even less willing to let West Berlin fall to the Soviets. He considered the West Berlin area to be a strategic area of influence for the Western Allies. He also believed he could not abandon the West Berliners and that surrendering to the Soviets would make the US seem weak.
And so the US responded to the blockade in a non-violent way. Thus came the Berlin Airlift. For a year since 1948, the US flew in food and supplies to the West Berliners by way of helicopter. Together, US and British forces delivered 2.3 million tons. In addition, the famed 'Candy Bomber,' Gail Halvorsen, dropped candy with parachutes to the children of West Berlin. The Soviets eventually withdrew the blockade and the Airlift's effects were to increase pride and trust in the United States.
Sources: Spirit of Freedom.org, Wikipedia, Hill Air Force Base