The Armenian language (classical: հայերէն; reformed: հայերեն [hɑjɛˈɾɛn] hayeren) is the official language of Armenia and Nagorno-Karabakh Republic. It is spoken by 8 to 12 million people. It has historically been spoken throughout the Armenian Highlands and today is widely spoken in the Armenian diaspora. Armenian has its own unique script, the Armenian alphabet, introduced in 405 AD by Mesrop Mashtots.

Armenian is an independent branch of the Indo-European languages. It is of interest to linguists for its distinctive phonological developments within that family. Armenian exhibits more satemization than centumization, although it is not classified as belonging to either of these. Some linguists tentatively conclude that Armenian, Greek (Phrygian), Albanian and Indo-Iranian were dialectally close to each other; within this hypothetical dialect group, Proto-Armenian was situated between Proto-Greek (centum subgroup) and Proto-Indo-Iranian (satem subgroup).[28]

Armenia was a monolingual country by the 2nd century BC at the latest. Its language has a long literary history, with a 5th-century Bible translation as its oldest surviving text. Its vocabulary has been influenced by Western Middle Iranian languages, particularly Parthian, and to a lesser extent by Greek, Persian, and Arabic throughout its history. There are two standardized modern literary forms, Eastern Armenian and Western Armenian, with which most contemporary dialects are mutually intelligible.

Armenian has official status as a minority language in Cyprus, Poland and Romania. Until the the early 1990s schools in Armenian taught in either Armenian or Russian, however after the collapse of the USSR, Armenian became the main medium of instruction and the Russian-medium schools were closed. In 2010 Russian language education was reintroduced in Armenia. There are also Armenian speakers in many other countries, including Russia, Georgia, Lebanon, Iran, Syria, Turkey, Egypt and the USA.

The two main modern forms of Armenian emerged during the 19th century when the traditional Armenian homeland was divided between the Russian and Ottoman Empires. Western Armenian developed among Armenians who had moved to Constantinople, while Eastern Armenian developed among Armenians living in Tbilisi in Georgia. Many newspapers in each of the variants were published and many schools for each variety were set up. This resulted in widespread literacy and to an increase in the amount of literature written in modern Armenian, rather than in the classical language.

Although the Armenians were known to history much earlier (for example, they were mentioned in the 6th century BC Behistun Inscription and in Xenophon's 4th century BC history, The Anabasis), the oldest surviving Armenian-language text is the 5th century AD Bible translation of Mesrop Mashtots, who created the Armenian alphabet in 405 AD, at which time it had 36 letters. He is also credited by some with the creation of the Caucasian Albanian alphabet and the Georgian scripts. In The Anabasis, Xenophon describes many aspects of Armenian village life and hospitality in around 401 BC. He relates that the Armenian people spoke a language that to his ear sounded like the language of the Persians.

Sources:
Wikipedia
http://www.omniglot.com/writing/armenian.htm