A five-continent model used in some areas of the world lists the continents as: Eurasia, the Americas, Africa, Australia and Antarctica. This is just one of many models used to delineate the Earth's continents.
Some models used to determine the number and borders of the Earth's landmasses, such as the one most commonly used in the United States, divide the world into seven continents, which splits Europe from Asia and North America from South America. The European model views North and South America as one continent. Due to these difficulties, geographers have, instead, divided the Earth into regions based on geography, culture and other factors to simplify their studies.