The Auschwitz was about 40 kilometers large; not including the places the prisoners couldn't go. The camp was swampy and of course a terrible living condition for the prisoners. This camp and many others were started because the Nazi's thought so many Jews were going to come in and they would have no place to put them. They needed a big facility that killed millions of people.
Rudolf Hoss was a man who was in charge of these mass killings at Auschwitz. He was the First Commander of the camp and organized these deaths. Arthur Liebehenschel took over when Hoss left. Then Himmler followed him and was later imprisoned. All of these commanders had come from other camps.
Other camps would take prisoners to Auschwitz for cheap labor. They prisoners were forced to make rubber and plant. They were also forced to build mines. All of these prisoners were tattooed so when they took role they knew you were there. 1.3 million people had passed through the camp, and this doesn't include the prisoners that were gassed right away. The reason so many people went there was because it was one of the largest concentration camps ever.
All of the Concentration Camps had special killing techniques. Auschwitz gassed people. Gas Chamber 1 killed 1000 Jews right when they first got there but was discontinued after the camp got Gas Chamber 2. Gas Chamber 3 was used from March 1943 to November 1944. It killed over 1440 prisoners every hour. After the prisoners were killed they were sent to the crematoriums.
Crematorium 1 could burn 340 people every 24 hours. Zyklon B was the gas used to kill these people in all of the camps. Crematorium 2 was destroyed late in the war to hide what the Nazi's had done.