What is the most common thing prisoners were fed in a concentration camp?
The usual thing was thin soup with some added cereal.
During the Holocaust, concentration camp prisoners received tattoos only at one location, the Auschwitz concentration camp complex, which consisted of Auschwitz I (Main Camp), Auschwitz II (Auschwitz-Birkenau), and Auschwitz III (Monowitz) and the subcamps. Incoming prisoners were assigned a camp serial number which was sewn to their prison uniforms and tattooed on the wrist. Only those prisoners selected for work were issued serial numbers; those prisoners sent directly to the gas chambers were not registered…
The first concentration camp was Dachau, it was opened on march 22nd 1933. The first prisoners were communists, because they were blamed for the Reichstag fire, that Hitler and the Nazis had planned to make it seem as if it were the communists fault, and Hitler "saved" the Germans from their actions and he "stopped" the fire. So they were sent to dachu, political prisoners
Prisoners of German and Japanese Concentration Camps were usually on starvation diets and were worked, generally to death. Many prisoners deemed "unfit to survive" were shot, hung, gassed and then buried in mass graves or cremated and then the ashes spread to the winds. Other camps, such as the Star Camp and Hungarian Camp, the inmates were treated decently.
Auschwitz concentration camp was the largest concentration camp of Nazi Germany. The living conditions were very poor and the prisoners were worked until they could work no more then they were killed. All the prisoners were fed not enough calories to keep them going. Around 100 people were in one room altogether.