The Cold War was a rivalry between the United States and the Soviet Union. It wasn't really a war because no physical fighting actually occurred. The countries were the most powerful countries in the world at the time, and they both wanted to have control with their government systems. They represented two opposing systems of government. The United States has Capitalism and The Soviet Union had Communism.
Because both counties were afraid of attacks from each other, they spent a great percentage of their GNP on military build up. That is less money that can be spent on other things. For the Soviet Union, less money was spent to provide for the people (medical care, food, housing, schools, and more). This eventually led to the collapse of the Soviet Union. The Cold War also led to the Arms Race and Nuclear Weapon build up around the world. Military technology led to the spread of knowledge of military and nuclear technologies to some countries that did not have it before (some of those countries, like North Korea, are dangerous with this knowledge).
