The Cold War started right after WWII in 1947 and lasted all the way until 1991. It wasn’t an actual physical war, it only contained the threats of nuclear war between countries.
The main causes of the Cold War were: both countries had nuclear weapons and threatened each other, Truman disliked Stalin and his communism, while Stalin disliked Truman and his capitalism, etc.
The Cold War had significant effects on society. Primarily, it ended communism, and Russia’s military spending was cut quickly.
World History Blog 