The first and last president of the Soviet Union Mikhail Gorbachev marks his 90th birthday on Tuesday.

Gorbachev served on the top post for six years. Shortly after his appointment as the General Secretary of the Communist Party in 1985 he chaired the Supreme Soviet of the Soviet Union (legislative body) and suggested creating the post of a president and abolishing an article of the Constitution on the leading role of the party.

Many languages across the world at that moment added Russian words "perestroika" and "glasnost."

Today Gorbachev is still sure that his decisions were right, describing perestroika as the greatest achievement of his life, for it helped abolish the totalitarian system. "Perestroika, of course, and everything that goes with it," he told TASS in an interview. "It is my profound conviction that perestroika was necessary, and that we were moving in the right direction. Our greatest achievement inside the country was that people gained freedom and put an end to the totalitarian system."