The Eastern Bloc refers to those countries occupied by the Soviet Union towards the end of World War II in 1945, which became Soviet puppet-states with the establishment of (gradually or immediate) communist governments.
These included Estonia, Latvia, Lithuania, Poland, Romania, Bulgaria, Czecho-Slovakia, Hungary, and East Germany. Albania and Yugoslavia initially came under Soviet influence too but ultimately became communist states independent of the Soviet Union.
These countries were considered as being behind the communist Iron Curtain.
Communism in Europe collapsed in 1990-1992 and these countries, including Russia, became independent plutocratic liberal 'democracies'.