TheUnited States of America(USA), commonly referred to as theUnited States(U.S.) orAmerica, is afederal republic composed of 50states, afederal district, five majorterritoriesand variouspossessions.It is one of the world's mostethnically diverseandmulticulturalnations, the product of large-scaleimmigration from many countries. countries.Thegeographyandclimate of the United Statesare 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.