The Indo-European languages include 150 languages spoken by about 3 billion people, most of the major language families of Europe and western Asia which belong to a single superfamily.
The hypothesis that this was so was first proposed by Sir William Jones, who noticed similarities between four of the oldest languages known in his time, Sanskrit, Latin, Greek,and Persian. Systematic comparison of these and other old languages conducted by Franz Bopp supported this theory. In the 19th century, scholars used to call the group "Indo-Germanic languages". However when it became apparent that the connection is relevant to most of Europe's languages, the name was expanded to Indo-European. An example of this was the strong similarity discovered between Sanskrit and olden dialects of Lithuanian.
The common ancestral (reconstructed) language is called Proto-Indo-European (PIE). There is disagreement as to the geographic location where it originated from, with Armenia and the area to the north or west of the Black Sea being prime examples of proposed candidates.
The various subgroups of the Indo-European family include:
Most spoken European-languages belong to the Indo-European superfamily. There are, however, language families which do not. The Finno-Ugric language family, which includes Hungarian, Estonian, Finnish and the languages of the Saami, is an example. The Caucasian language family is another. The Basque language is unusual in that it appears to be separate from all other language families.
The Maltese language and Turkish are two examples of languages spoken in Europe which have definite non-European origins. Turkish being Turkic, and Maltese being largely derived from Arabic
It has been proposed that Indo-European languages are part of the hypothetical Nostratic language superfamily; this theory is controversial.1