Mikhail Sergeyevich Gorbachev is a Russian and former Soviet politician. The eighth and final leader of the Soviet Union, he was the General Secretary of the Communist Party of the Soviet Union from 1985 until 1991. He was also the country's head of state from 1988 until 1991, serving as the chairman of the Presidium of the Supreme Soviet from 1988 to 1989, chairman of the Supreme Soviet from 1989 to 1990, and president of the Soviet Union from 1990 to 1991. Ideologically, Gorbachev initially adhered to Marxism–Leninism, although he had moved towards social democracy by the early 1990s.