What was peristroika; why did Gorbachev introduce it; and why did peristroika fail?

On taking office in 1985 Mikhail Gorbachev inherited a Soviet economy with a sagging rate of industrial and agricultural output which was in desperate need of reform. Gorbachev chose to adjust the old system with a period of perestroika. Perestoika translated literally means restructuring and was the term attached to the attempts (1985-91) by the Prime Minister to transform the stagnant, inefficient command economy of the Soviet Union into a decentralized market-oriented economy. However, it was …

…slow, gradual economic reforms annulled any positive effects that the reforms might have had. Gorbachev's main mistake was that he destroyed the old system without putting a new one in to take its place. His long-term plans were not only vague but also altered considerably over time. The pulled the foundations from under the USSR without making plans for reconstruction in the aftermath, and was then surprised when the whole system collapsed around his ears.