Final answer:
Mikhail Gorbachev's policies of perestroika and glasnost aimed to save the USSR by modernizing it but instead led to its collapse. Economic weaknesses were exposed, autonomy and independence movements gained momentum, and a failed conservative coup in 1991 precipitated the end of the Soviet Union and the Cold War.
Step-by-step explanation:
Mikhail Gorbachev's policies of perestroika (economic restructuring) and glasnost (openness and transparency in government) aimed to modernize and revitalize the Soviet Union. However, these reforms inadvertently exposed deep economic flaws and fueled demands for greater autonomy among the Soviet republics and independence movements in Eastern Europe. The subsequent political and social upheavals, combined with the economic strain and the loss of satellite states, led to the dissolution of the Soviet Union in 1991.
In this process, Gorbachev faced resistance from conservative factions within the Communist Party, culminating in a failed coup attempt in August 1991. Boris Yeltsin, the president of the Russian Soviet Federative Socialist Republic, played a significant role in opposing the coup, and later, alongside other republic leaders, voted to dissolve the Soviet Union, signaling the end of the Cold War.
The breakdown of centralized control and the incorporation of market-like reforms under perestroika weakened the Soviet economy further, discrediting the Communist Party. Coupled with the newfound freedom of speech from glasnost, there was a surge in democratic sentiments, which hastened the collapse of the Communist regime and set the stage for the rise of democratic governments in the post-Soviet era.