Although many people called all the camps Concentration Camps there were many different types of camps. For example there were extermination camps, labor camps, prisoner-of-war camps, transit camps and death camps. One of the first concentration camps was Dachau, which opened on March 20, 1933. From 1933-1938 many of the prisoners were people who spoke against the Nazis or Hitler. Life within Nazi concentration camps was horrible. Prisoners were forced to do hard physical labor and yet given tiny rations of food . Prisoners slept three or more people per crowded wooden bunk (no mattress or pillow). Torture in the concentration camps was common and deaths were frequent. Many of the Doctors that were in the concentration camps conducted experiments on the prisoners against their will. One of the biggest concentration camps was Auschwitz and it was estimated that 1.1 million people were killed there . This camp was so big because it was a combination of a concentration camp and an extermination camp .