A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are (from largest in size to smallest): Asia, Africa, North America, South America, Antarctica, Europe, and Australia.
Plate tectonics is the geological process and study of the movement, collision and division of continents, earlier known as continental drift.
Conventionally, “continents are understood to be large, continuous, discrete masses of land, ideally separated by expanses of water.” Many of the seven most commonly recognized continents identified by convention are not discrete landmasses separated by water. The criterion “large” leads to arbitrary classification: Greenland, with a surface area of 2,166,086 square kilometres (836,330 sq mi) is considered the world’s largest island, while Australia, at 7,617,930 square kilometres (2,941,300 sq mi) is deemed to be a continent. Likewise, the ideal criterion that each be a continuous landmass is often disregarded by the inclusion of the continental shelf and oceanic islands, and contradicted by classifying North and South America as two continents; and/or Eurasia and Africa as two continents, with no natural separation by water. This anomaly reaches its extreme if the continuous land mass of Europe and Asia is considered to constitute two continents. The Earth’s major landmasses are washed upon by a single, continuous world ocean, which is divided into a number of principal oceanic components by the continents and various geographic criteria.
The narrowest meaning of continent is that of a continuous area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. In this sense the term continental Europe (sometimes “the Continent”) is used to refer to mainland Europe, excluding islands such as Great Britain, Ireland, and Iceland, and the term continent of Australia may refer to the mainland of Australia, excluding Tasmania and New Guinea. Similarly, the continental United States refers to the 48 contiguous states in central North America and may include Alaska in the northwest of the continent (the two being separated by Canada), while excluding Hawaii in the middle of the Pacific Ocean.
From the perspective of geology or physical geography, continent may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area (the continental shelf) and the islands on the shelf (continental islands), as they are structurally part of the continent. From this perspective the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level. In this sense the islands of Great Britain and Ireland are part of Europe, while Australia and the island of New Guinea together form a continent.
As a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments. In this way, Iceland is considered part of Europe and Madagascar part of Africa. Extrapolating the concept to its extreme, some geographers group the Australasian continental plate with other islands in the Pacific into one continent called Oceania. This allows the entire land surface of the Earth to be divided into continents or quasi-continents.
To sum it all, there are just seven continents and there exist nations and define government in each one of them. These seven continents are;

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