The Russian Language: Origin
The Russian language is the most widespread one among the Slavonic languages. It is spoken in most post-soviet countries, while in Russia they mostly speak only Russian. In some post-soviet countries they may not write or read in Russian these days, but they still use it a lot in speech and verbal expression. All Slavonic languages have many common elements, but it’s only Ukrainian and Byelorussian that are the most similar ones to Russian.
The similarity of Slavonic languages is due to the fact that they all originated from one Common Slavonic, or Common Slavic language, which broke up into several languages when the Slavonic commune fell apart into different tribes. That is why the Russian language may be called a Slavonic dialect. The Common Slavonic in its turn had originated from a Indo-European language which makes the Russian Language related to Teutonic, Latin, Greek and other languages.
The Russian written language came from the Greek alphabet in the 9th century AD and was used by most Slavonic tribes: Bulgarians, Serbians, Croats, Czechs, Slovaks, Ukrainians, Belorussians and Russians. The Early History of Cyrillic Alphabet explains why some Russian letters are very similar to Greek ones and proves their affinity.