Realism is a way of thinking about how countries interact with each other. It became popular because of some important events in history. Here are the main reasons why:

• Uncertainty After WWII: After the Second World War, there was a lot of confusion. Countries were worried about their safety. They started to focus on protecting themselves and their own interests.

• Cold War Competition: During the Cold War, two powerful countries, the USA and the USSR, were in a big rivalry. This made nations realize that having a strong military and looking out for their own interests were very important.

• Beliefs About Human Nature: Realism also suggests that people can be selfish and power-hungry. This view matches up with many conflicts and struggles for power throughout history.

Because of these reasons, realism became a widely accepted way to understand international relations.