In Portuguese, América is a single continent composed of América do Sul (South America), América Central (Central America) and América do Norte (North America). It can be ambiguous, as América can be used to refer to the United States of America, but is avoided in print and formal environments.
The six-continent combined-America model is often used in Latin America, Greece, and countries that speak Romance languages. The United Nations  and in the Olympic Charter  in its description of the Olympic flag derived the five-continent model from the combined-America model by excluding Antarctica as uninhabited.
The first continent system is the seven continent system consisting of Europe, Asia, Africa, Oceania / Australia, North America, South America and Antarctica. The six continent system is essentially the same as the seven continent system, the only difference being two continents are merged.
North America covers an area of about 24,709,000 square kilometers (9,540,000 square miles), about 16.5% of the Earth's land area and about 4.8% of its total surface. North America is the third-largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe.
See Article History. North America, third largest of the world’s continents, lying for the most part between the Arctic Circle and the Tropic of Cancer. It extends for more than 5,000 miles (8,000 km) to within 500 miles (800 km) of both the North Pole and the Equator and has an east-west extent of 5,000 miles.
United States, officially United States of America, abbreviated U.S. or U.S.A., byname America, country in North America, a federal republic of 50 states.
In Ibero-America (Spanish and Portuguese speaking American countries), the Americas is considered a single continent, and Central America is considered a subregion of the Americas comprising the seven countries south of Mexico and north of Colombia.
Continent model: In some parts of the world, for example, Latin America, Latin Europe, and Iran, South America is viewed as a subcontinent of the Americas (a single continent named America). In most of the countries with English as an official language, however, it is considered a continent ; see Americas (terminology) .