Millions of Jews were forced labourers in ghettos, before they were shipped off to extermination camps. The Nazis also operated concentration camps, some of which provided free forced labour for industrial and other jobs while others existed purely for the extermination of their inmates. To mislead the victims, at the entrances to a number of camps the lie "work brings freedom" ("arbeit macht frei") was placed, to encourage the false impression that cooperation would earn release.