Russian (русский язык, transliteration: russkiy yazyk, Russian pronunciation: [ˈruskʲɪj jɪˈzɨk], meaning 'Russian language') is the most geographically widespread language of Eurasia, the most widely spoken of the Slavic languages, and the largest native language in Europe. Russian belongs to the family of Indo-European languages and is one of three (or four including Rusyn) living members of the East Slavic languages. Written examples of Old East Slavonic are attested from the 10th century onwards. The language is one of the six official languages of the United Nations.

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 mixture, e.g. Surzhyk in eastern Ukraine and Trasianka in Belarus. An East Slavic Old Novgorod dialect, although vanished during the fifteenth or sixteenth century, is sometimes considered to have played a significant role in the formation of the modern Russian language. The next closest relatives are the West Slavic languages, especially Polish and Slovak; next are the South Slavic languages, but Bulgarian especially has somewhat different grammar.