The Nazis revived the medieval term ghetto to describe their device of concentration and control, the compulsory "Jewish Quarter." Ghettos were usually established in the poor sections of a city, where most of the Jews from the city and surrounding areas were subsequently forced to reside. Often surrounded by barbed wire or walls, the ghettos were sealed. Established mostly in eastern Europe (e.g., Lodz, Warsaw, Vilna, Riga, or Minsk), the ghettos were characterized by overcrowding, malnutrition, and heavy labor. All were eventually dissolved, and the Jews murdered. Concentration camps were prisons used without regard to accepted norms of arrest and detention. They were an essential part of Nazi systematic oppression. Initially (1933-36), they were used primarily for political prisoners. Later (1936-42), concentration camps were expanded and non-political prisoners--Jews, Gypsies, homosexuals, and Poles--were also incarcerated. In the last period of the Nazi regime (1942-45), prisoners of concentration camps were forced to work in the armament industry, as more and more Germans were fighting in the war. Living conditions varied considerably from camp to camp and over time. The worst conditions took place from 1936-42, especially after the war broke out. Death, disease, starvation, crowded and unsanitary conditions, and torture were a daily part of concentration camps.