Papua New Guinea is the most linguistically diverse country in the world. It is a reasonably small country, in relative land size and population size, but has over eight hundred spoken languages and several dead languages that are not spoken but are still understood. Papua New Guinea’s unique linguistic makeup is primarily a by-product of social customs that limit interactions between various tribal groups, as well as the geographic isolation of many regions of the country.

Persian is part of the Iranian language branch of the Indo-European language family. Yiddish, a High German language, and Sanskrit, an ancient Indian language, are the only other languages on this list that are part of the Indo-European language family. Hebrew is a Semitic language, part of the Afro-Asiatic language family, and Tibetan is part of the Sino-Tibetan language family.

The Hellenic language branch is a part of the Indo-European language family. Greek is the only major language in the world that falls under the category of Hellenic. The name “Hellenic” comes from the Greek word for their own country "Hellas."

An “isogloss” is a boundary line between two distinct linguistic regions. It can be a boundary between two different languages, or, more frequently, the boundary between two different dialects of the same language. One commonly used example is the different ways Americans refer to carbonated beverages. In some parts of the country Americans say “Soda,” “Pop,” “Soft Drinks,” and so on. In England these drinks are called “Fizzy Drinks.” When geographers draw a map reflecting the different regional terms for carbonate beverages the boundary where one term fades from use and another moves to the forefront is called an “isogloss.”

A “dialect” is a regional variety of a language. Although it often manifests itself in different accents, this is not the only way this can occur. Although people in southern England and the west coast of the United States speak the same language, they also have phrases and words that the other would not use: different expressions, different mannerisms, and, yes, different accents. This is true throughout the English-speaking world (think about the difference between Australian, Canadian, American, and English ways of speaking). And it is also true for every other widespread or international language. People develop new ways of thinking and new phrases when placed in relative geographic isolation. In England, where the homogenizing impact of modern technology has had less relative time to affect change, dialects can change dramatically every hundred miles.

A “pidgin” language often emerges when two or more languages coexist in a small geographic area. It involves the natural combination of two or more languages into one fluid and changeable dialect. Pidgin’s are often incomprehensible to speakers of the original languages, and may even contain some words that are completely unrelated to either of the languages. By their nature pidgin languages are generally fluid and transitory.

The word “Nostratic” is used to describe a hypothesized proto-macrolanguage family that was spoken by people somewhere in Asia roughly fifteen thousand years ago. According to the theory, all Indo-European, Dravidian, Afro-Asiatic, Uralic, and Kartvelian languages derive from this one macrolanguage. The theory is widely contested by many geographers, but is extremely influential in the field of linguistic geography.  

Bengali is part of the Indian language branch of the Indo-European language family. It is widely spoken by people in eastern India and Bangladesh. It is in fact the only language on this list that is even part of the Indo-European language family, let alone part of the Indian branch. Hebrew is a Semitic language and part of the Afro-Asiatic language family. Burmese and Cantonese are part of the Sino-Tibet language family. Thai is a branch of the Tai-Kadai language family.

Switzerland, which has an ethnically and linguistically diverse population, recognizes four official national languages - French, German, Italian, and Romansh. Spanish is not an official or widely used language in Switzerland. Romansh is spoken by a very small number of Swiss people but is still recognized by the Swiss government for a variety of historical reasons.

Indo-European, the language family that includes all European languages (which are widely spoken in Europe, the Americas, Africa, and Australasia) and Indian and Iranian, is spoken by slightly over fifty percent of the world’s population. The next largest is Sino-Tibet which is spoken by close to a quarter of the world’s population.