German reunification (German: Deutsche Wiedervereinigung) was the process in which the German Democratic Republic (GDR/East Germany) joined the Federal Republic of Germany (FRG/West Germany), and Berlin was united into a single city-state. The start of this process is commonly referred by Germans as die Wende (The Turning Point.). The end of the unification process is officially referred to as the German unity (German: Deutsche Einheit), celebrated on 3 October (German Unity Day).

The East German regime started to falter in the summer of 1989, when Hungary opened a hole in the Iron Curtain. It caused an exodus of thousands of East Germans fleeing to West Germany and Austria 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, whilst negotiations between the GDR and FRG and the four occupying powers produced the so-called "Two Plus Four Treaty" (Treaty on the Final Settlement with Respect to Germany) granting full sovereignty to a unified German state, whose two halves had previously still been bound by a number of limitations stemming from its post-WWII-status as an occupied nation. The united Germany remained a member of the European Community (later the European Union) and of NATO.