In today's world there are about 4 thousand people (ethnic groups). Ethnos (Greek - "tribe", the "people") - well-established community of people that existed historically in a certain area, and has its own language, culture, mentality.
common language has always been and remains an important factor in bringing people into tribes - ethnic groups - nations - the nations among which the most numerous (over 100 million), Chinese (more than 1 billion people.) hindustantsy (over 220 million pers.), Americans United States (about 200 million people.) Bengali (about 180 million people.) Russian (about 145 million people.) Brazilians (about 140 million people.) Japanese (about 120 million people)..
Every nation is inherent in their own language, but there are cases where the same language spoken several nations, and vice versa - some of the same people use different languages. Linguistic affinity as the basis for classifying people. Emit nearly twenty language families that are divided into linguistic groups.
most numerous - Indo-European family, whose language is spoken by about 50% of the population (more than 150 nations and nationalities). As part of this family gives 11 language groups. The most numerous among them are Indo-Aryan, Roman, Germanic, Slavic, Iranian.
second major language family is a Sino-Tibetan (Sino-Tibetan). At its languages are spoken by approximately 22% of the population. Next come the Altai, the Niger-kordofanskaya, Afro-Asiatic (Semitic-Hamitic) and others.
The most common languages of the world belong to Chinese, English, Hindi, Spanish and Russian.
by national (ethnic) composition of the population of all countries are divided into mononational and multinationals. Mononational countries arise in the coincidence of ethnic and political boundaries. These countries dominate in Europe, Latin America, South-West Asia. In a world dominated by multinational countries (India, Pakistan, China, Russia, USA, Indonesia, etc.). Belong to this group, and a binational country: Belgium, Canada. For multinational countries is characteristic of a federal administrative-territorial units. Unitary countries tend to be monoethnic.