The German concept of Lebensraum (German pronunciation: [ˈleːbənsˌʁaʊm], English: "living space") refers to policies and practices of settler colonialism proliferated in Germany from the 1890s to the 1940s. The most extreme form of this ideology was supported by the Nazi Party (NSDAP) in the Third Reich until the end of World War II. First popularized around 1901,Lebensraum became a geopolitical goal of Imperial Germany in World War I (1914–1918) originally, as the core element of the Septemberprogramm of territorial expansion.
Following Adolf Hitler's rise to power Lebensraum became an ideological principle of Nazism, and provided justification for the German territorial expansion into East-Central Europe. The Nazi Generalplan Ost policy (the Master Plan for the East) was based on its tenets. It stipulated that most of the indigenous populations of Eastern Europe would have to be removed permanently (either through mass deportation to Siberia, death, or enslavement) including Polish, Ukrainian, Russian, and other Slavic nations considered racially inferior. The Third Reich aimed at repopulating these lands with Germanic colonists in the name of Lebensraum during World War II and thereafter. The entire populations were to be decimated by starvation, allowing for their own agricultural surplus to feed Germany.
Hitler’s strategic program for world domination was based on the belief in the power of Lebensraum, pursued by a racially superior society. People deemed to be part of inferior races, within the territory of Lebensraum expansion, were subjected to expulsion or destruction. The eugenics of Lebensraum assumed the right of the German Aryan master race (Herrenvolk) to remove indigenous people they considered to be of inferior racial stock (Untermenschen) in the name of their own living space. Nazi Germany also supported other 'Arian' nations' pursuing their own Lebensraum, including Fascist Italy's Spazio vitale.