Global interdependence means that people and nations all over the world now depend on one another for many goods and services. It also means that what happens in one nation or region affects what happens in other places. The most important part of economic interdependence is trade. Two of the biggest global challenges are the growing economic inequality between nations and the destruction of the environment.

One of the results of World War I was the formation of the League of Nations. The League was too weak, however, to prevent the outbreak of World War II. In 1945, the United Nations was formed. Today the UN has 189 members. The goal of the UN is to maintain peace and improve the lives of people all over the world. In 1948 the United Nations adopted what has become the most important human rights document of the post-World War II years—the Universal Declaration of Human Rights. Following the terrorist attacks in September 2001, President George W. Bush reaffirmed the United States' commitment to freedom for all.