During the war, ghettos, transit camps, and forced labor camps, in addition to the concentration camps, were created by the Germans and their collaborators to imprison Jews, Gypsies, and other victims of racial and ethnic hatred, as well as political opponents and resistance fighters. Following the invasion of Poland, three million Polish Jews were forced into approximately 400 newly established ghettos where they were segregated from the rest of the population. Large numbers of Jews were also deported from other cities and countries, including Germany, to ghettos in Poland and German-occupied territories further east.
In Polish cities under Nazi occupation, like Warsaw and Lodz, Jews were confined in sealed ghettos where starvation, overcrowding, exposure to cold, and contagious diseases killed tens of thousands of people. In Warsaw and elsewhere, ghettoized Jews made every effort, often at great risk, to maintain their cultural, communal, and religious lives. The ghettos also provided a forced labor pool for the Germans, and many forced laborers (who worked on road gangs, in construction, or other hard labor related to the German war effort) died from exhaustion or maltreatment.
Between 1942 and 1944, the Germans moved to eliminate the ghettos in occupied Poland and elsewhere, deporting ghetto residents to "extermination camps," killing centers equipped with gassing facilities, located in Poland. After the meeting of senior German government officials in late January 1942 at a villa in the Berlin suburb of Wannsee, the decision to implement "the final solution of the Jewish question" became formal state policy and Jews from western Europe were also sent to killing centers in the East.