What seperates continents?

Question

What seperates continents, how are North and South America not considered one continent, as well as Africa, Asia & Europe one continent.

If mountains ranges are something that seperates continents like they seperate Asia, Europe

then why arent there like 4 or 5 continents in North & South America where there are different mountain ranges.

why isnt africa, europe & asia one continent since the only things seperating them would be tectonic plates or the Suez Canal in Egypt which is man made and not natural.

North and South America also have nothing natural that seperates them besides tectonic plates

If tectonic plates are used for determining a continent then why arent there like 23 continents since there are 23 plates

Answer 1

Continent definition from Answers.com:  One of the principal land masses of the earth, usually regarded as including Africa, Antarctica, Asia, Australia, Europe, North America, and South America.

Definition from Geography/About.com: The major land masses of the earth. According to tradition most people speak of seven continents on the planet. However, geologically there are six large distinct land masses on the earth so many geographers and scientists refer to six.

Those who consider there to be seven continents refer to a separate Europe and Asia (divided at the Ural Mountains in western Russia) while those who prefer six continents refer to the joined land mass (and single tectonic plate) as Eurasia. In some countries, the Americas are combined into one continent.

Examples: The six continents include Africa, Antarctica, Australia, Eurasia, North America, and South America. The seven continents include Africa, Antarctica, Australia, Asia, Europe, North America, and South America.

As you can see, continent is defined rather loosely.  They are mostly surrounded by water, but, as you said Europe and Asia are together and are connected to Africa, and the Americas are connected by Central America.