Russian (ру́сский язы́к, russkiy yazyk, pronounced [ˈruskʲɪj jɪˈzɨk] ( listen)) is an East Slavic language and an official language in Russia, Belarus, Kazakhstan, Kyrgyzstan and many minor or unrecognised territories. It is an unofficial but widely-spoken language in Ukraine, Latvia, Estonia, and to a lesser extent, the other countries that were once constituent republics of the Soviet Union and former participants of the Eastern Bloc. Russian belongs to the family of Indo-European languages and is one of the three living members of the East Slavic languages. Written examples of Old East Slavonic are attested from the 10th century onwards.
What language sub-family is Russian in?
East Slavic