Final answer:
The Korean War was caused by the division of Korea and resulted in the establishment of the 38th Parallel as the boundary between North and South Korea. It also contributed to the Cold War rivalry between the United States and the Soviet Union.
Step-by-step explanation:
The Korean War was caused by a number of factors. The main cause was the division of Korea into two separate countries following World War II. The North, led by the communist regime of Kim Il-sung, wanted to reunify Korea under communist rule, while the South, supported by the United States and other Western nations, wanted to maintain capitalist democracy. This led to tensions and eventually to war.
The effects of the Korean War were significant. Firstly, the war resulted in the establishment of the 38th Parallel as the boundary between North and South Korea, which remains in place to this day. Additionally, the war contributed to the Cold War rivalry between the United States and the Soviet Union, as the United States intervened to stop the spread of communism. The war also had a devastating human cost, with millions of people killed or displaced.