Mikhail Gorbachev was the last leader of the Soviet Union, serving as general secretary and president, and is known for his policies of glasnost and perestroika that promoted democratic reforms and ultimately contributed to the union's collapse in 1991. He played a significant role in ending the Cold War and transformed foreign relations, particularly with the United States, working with President Reagan to reduce tensions. The USSR, officially known as the Union of Soviet Socialist Republics, was a federal union formed in 1922, which dissolved in 1991 following economic stagnation and political reforms.