German reunification was the process in 1990 in which the German Democratic Republic became part of the Federal Republic of Germany to form the reunited nation of Germany.
The end of the unification process is officially referred to as German unity, celebrated each year on 3 October as German Unity Day. East and West Berlin were reunited into a single city, and again became the capital of united Germany.
The East German government started to falter in May 1989, when the removal of Hungary's border fence with Austria opened a hole in the Iron Curtain. The border was still closely guarded, but the Pan-European Picnic and the indecisive reaction of the rulers of the Eastern Bloc set in motion an irreversible peaceful movement. It allowed an exodus of thousands of East Germans fleeing to West Germany via Hungary. The Peaceful Revolution, a series of protests by East Germans, led to the GDR's first free elections on 18 March 1990, and to the negotiations between the GDR and FRG that culminated in a Unification Treaty.