Russian (русский язык, tr. rússkiy yazýk) is an East Slavic language, which is official in the Russian Federation, Belarus, Kazakhstan and Kyrgyzstan, as well as being widely used throughout Eastern Europe, the Baltic states, the Caucasus and Central Asia. It was the de facto language of the Soviet Union until its dissolution on 25 December 1991. Although nearly three decades have passed since the breakup of the Soviet Union, Russian is used in official capacity or in public life in all the post-Soviet nation-states, as well as in Israel and Mongolia.
Russian belongs to the family of Indo-European languages, one of the four living members of the East Slavic languages, and part of the larger Balto-Slavic branch. Written examples of Old East Slavonic are attested from the 10th century onward.
Russian is the largest native language in Europe and the most geographically widespread language in Eurasia. It is the most widely spoken of the Slavic languages, with 144 million speakers in Russia, Ukraine and Belarus. Russian is the eighth most spoken language in the world by number of native speakers and the seventh by total number of speakers. The language is one of the six official languages of the United Nations. Russian is also the second most widespread language on the Internet after English.
Russian distinguishes between consonant phonemes with palatal secondary articulation and those without, the so-called soft and hard sounds. Almost every consonant has a hard or a soft counterpart, and the distinction is a prominent feature of the language. Another important aspect is the reduction of unstressed vowels. Stress, which is unpredictable, is not normally indicated orthographically though an optional acute accent may be used to mark stress, such as to distinguish between homographic words, for example замо́к (zamók, meaning a lock) and за́мок (zámok, meaning a castle), or to indicate the proper pronunciation of uncommon words or names.