Russian (ру́сский язы́к, russkij jazyk, pronounced [ˈruskʲɪj jɪˈzɨk] is a Slavic language spoken primarily in Russia, Belarus, Ukraine, Kazakhstan, and Kyrgyzstan. It is an unofficial but widely spoken language in Moldova, Latvia, Estonia, and to a lesser extent, the other countries that were once constituent republics of the USSR. Russian belongs to the family of Indo-European languages and is one of three living members of the East Slavic languages. Written examples of Old East Slavonic are attested from the 10th century onwards.
It is the most geographically widespread language of Eurasia and the most widely spoken of the Slavic languages. It is also the largest native language in Europe, with 144 million native speakers in Russia, Ukraine and Belarus. Russian is the 8th most spoken language in the world by number of native speakers and the 5th by total number of speakers. The language is one of the six official languages of the United Nations.
Russian distinguishes between consonant phonemes with palatal secondary articulation and those without, the so-called soft and hard sounds. This distinction is found between pairs of almost all consonants and is one of the most distinguishing features 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 (знак ударения, znak udareniya) may be used to mark stress (such as to distinguish between homographic words, for example замо́к (meaning lock) and за́мок (meaning castle), or to indicate the proper pronunciation of uncommon words or names).
Russian is a Slavic language Indo-European family. It is a lineal descendant of the language used in Kievan Rus. From the point of view of the spoken language, its closest relatives are Ukrainian and Belarusian, the other two national languages in the East Slavic group. In many places in eastern and southern Ukraine and throughout Belarus, these languages are spoken interchangeably, and in certain areas traditional bilingualism resulted in language mixtures, e.g. Surzhyk in eastern Ukraine and Trasianka in Belarus. An East Slavic Old Novgorod dialect, although vanished during the 15th or 16th century, is sometimes considered to have played a significant role in the formation of modern Russian. Also Russian has notable lexical similarities with Bulgarian due to a common Church Slavonic influence on both languages, as well as because of later interaction in the 19th–20th centuries, although Bulgarian grammar differs markedly from Russian. In the 19th century, the language was often called "Great Russian" to distinguish it from Belarusian, then called "White Russian" and Ukrainian, then called "Little Russian".