The United States of America is a federal republic located in North America, consisting of 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth-largest country by total area and is slightly smaller than the entire continent of Europe. With a diverse geography, climate, and wildlife, the U.S. is home to a wide variety of ecosystems, including forests, grasslands, deserts, and coastlines. The country has a population of over 331 million people, making it the third-most populous country in the world. The U.S. is a highly developed country, with the world's largest economy by nominal GDP. The country is known for its diverse culture, history, and influential role in global affairs.