Concentration camps were camps built by Nazi Germany to imprison and persecute millions of people. The camps varied in their uses, with some serving as forced labor camps, others as killing centers where over a million people were murdered through gas chambers, medical experiments, starvation, disease and overwork. The largest camp was Auschwitz, where about 1.1 million people were killed, while others like Dachau, Buchenwald and Bergen-Belsen held tens of thousands of prisoners in inhumane conditions.