The United States of America (USA), commonly referred to as the United States (U.S.) or America, is a federal republic composed of 50 states, a federal district, five major territories and various possessions. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. countries.The geography and climate of the United States are also extremely diverse, and the country is home to a wide variety of wildlife.

Home to the world's third-largest population, with over 318 million people, it includes both densely populated cities with sprawling suburbs and vast, uninhabited natural areas. With its history of mass immigration dating from the 17th century, it is a "melting pot" of cultures from around the world and plays a dominant role in the world's cultural landscape.