A federal constitutional republic comprised of 50 states and a federal district (Washington D.C.). The United States is one of the world's most ethnically diverse and multicultural nations, this is due to widespread immigration from multiple regions around the globe.
Economically, the United States has the largest nominal GDP in the world. Militarily, it has the largest defense budget in the world. Politically, it yields significant influence through partnerships such as NATO (North Atlantic Treaty Organization), and strong ties to individual countries such as the U.K., Japan, Israel, Canada, Australia and South Korea. Culturally, the U.S. continues to yield significant influence through Hollywood and other widely viewed pop culture media.
If it weren't for the United States the European Union would be known as either Nazi Germany or the U.S.S.R.