Short answers, pulled from the story.
West Berlin emerged as an enclave following the Potsdam Agreement of 1945 which divided Berlin into four occupation zones controlled by the United States, the United Kingdom, France, and the Soviet Union. The American, British, and French zones surrounded the eastern half of the city to create this unique political entity inside what would become East Germany.
The Berlin Blockade began on the 24th of June 1948 when the Soviets cut off all land access to West Berlin and ended on the 12th of May 1949. The Western Allies launched the Berlin Airlift in response which lasted until the 30th of September 1949 to deliver food and supplies through three designated air corridors.
Active immigration policies transformed West Berlin into home to at least 178,000 Turkish and Turkish German residents making it the largest Turkish community outside Turkey. Many people fleeing East Germany chose West Berlin as their destination both before and after the construction of the Berlin Wall.
East Germany began constructing the Berlin Wall on the 13th of August 1961 to physically seal off West Berlin from both East Berlin and its surrounding hinterland. The wall consisted of concrete barriers barbed wire armed towers and systematic sealing of all Eastern streets bridges paths windows doors gates and sewers opening toward the west.
On the 3rd of October 1990 the day Germany officially reunified East and West Berlin formally united as a single city-state joining the enlarged Federal Republic alongside Bremen and Hamburg. This event ended Western Allies occupation of West Berlin following the Two Plus Four Treaty signed by both German states and four wartime allies.