In politics and diplomacy, a superpower is a state that has a leading position in the international system, capable of projecting significant military power anywhere in the world. A leading professor of National Security Affairs, Alice Miller, defines a superpower as "a country that has the capacity to project dominating power and influence anywhere in the world, and sometimes, in more than one region of the globe at a time, and so may plausibly attain the status of global hegemon." The term was coined in 1944 by William T.R. Fox, an American foreign policy professor, in his book The Superpowers: The United States, Britain and the Soviet Union – Their Responsibility for Peace.

In 1944, when the term was coined, there were three superpowers: the United States, the British Empire, and the Soviet Union. At its height in 1922, the British Empire encompassed 25% of of the world's population and 25% of its land area. During World War II, due to the stresses of the war and numerous independence movements among its colonies, the British Empire fell from its place as a superpower, leaving only the United States and the Soviet Union. For the next few decades, throughout the time known as the Cold War, the rivalry between the remaining superpowers, the US and the USSR, set the tenor for world politics. A war between these two countries could have killed hundreds of millions of people and left hundreds of cities in ruin, but luckily this never happened.

When the Soviet Union collapsed in 1991, this left the United States as the world's sole remaining superpower. The word "hyperpower" has sometimes been used to describe the United States' current position, although the term has not achieved widespread acceptance. America's place as the new sole superpower may be part of the reason for the flourishing of anti-American sentiment in the late 90s and throughout the 00s. Some of the world's countries resent the United States' hegemonic power, and are particularly angry at its military activities in Afghanistan and Iraq, which they see as veiled imperialism.

Some observers believe that the next superpower to enter the scene may be China. According to some analysts, the Chinese economy will surpass that of the United States, in terms of purchasing power parity, by 2020. China's dizzying rate of new construction is a testament to their ascent on the world stage, and their recognized military buildup may seem threatening to others around the world, but it guarantees China a key position in international diplomacy.