How many continents are there in the world?
The most common answer to this question is 7, where the continents are Asia, Europe, Africa, North America, South America, Australia and Antartica. Some give 6 or 5 as the answer, where they combine Asia and Europe into Eurasia and/or combine North America and South America into Americas. A few people even say 8, where they consider the mostly submerged Zealandia to be a continent. However, all of the above answers are wrong.
In reality, there's only 3 continents in the world, which are Afro-Eurasia, America and Australia. The proper definition of a continent is a large and continuous landmass with permanent human population and biodiversity.
Asia and Europe are connected to each other over long stretches of land and there's nothing separating them at all, so it makes no sense to consider them as two separate continents.
Asia and Africa are separated only by the Suez Canal, while North America and South America are separated only by the Panama Canal. Since the Suez Canal and Panama Canal are artificial structures, they shouldn't be taken into consideration. Therefore, Asia and Africa are parts of the same continent, while North America and South America form a single America.
By extension, Asia, Europe and Africa form a single continent known as Afro-Eurasia.
In Antarctica, there isn't any permanent human population and there is very limited biodiversity due to the extreme climate. Therefore, Antarctica shouldn't be considered a continent.
Any submerged "continent" and any island smaller than Australia shouldn't be considered a continent. Since Zealandia is mostly underwater except for the islands of New Zealand which collectively are much smaller than Australia, it isn't a continent.
This makes the total number of continents only 3, no more and no less.