What was the "Polish Corridor"?

The Polish Corridor also known as Danzig Corridor, Corridor to the Sea or Gdańsk Corridor, was a territory located in the region of Pomerelia (Pomeranian Voivodeship, eastern Pomerania, formerly part of West Prussia), which provided the Second Republic of Poland (1920–1939) with access to the Baltic Sea, thus dividing the bulk of Germany from the province of East Prussia. The Free City of Danzig (now the Polish city of Gdańsk) was separate from both Poland and Germany. A similar territory, also occasionally referred to as a corridor, had been connected to the Polish Crown as part of Royal Prussia during the period 1466–1772.