The Auschwitz complex was divided in three major camps: Auschwitz I main camp or Stammlager; Auschwitz II, or Birkenau, established on October 8th, 1941 as a 'Vernichtungslager' (extermination camp); Auschwitz III or Monowitz, established on May 31th, 1942 as an 'Arbeitslager' or work camp; also several sub-camps. There were up to seven gas chambers using Zyklon-B poison gas and three crematoria. Auschwitz II included a camp for new arrivals and those to be sent on to labor elsewhere; a Gypsy camp; a family camp; a camp for holding and sorting plundered goods and a women's camp. Auschwitz III provided slave labor for a major industrial plant run by I G Farben for producing synthetic rubber (see Blechhammer). Highest number of inmates, including sub-camps: 155,000. The estimated number of deaths: 2.1 to 2.5 million killed in gas chambers, of whom about 2 million were Jews, and Poles, Gypsies and Soviet POWs. About 330,000 deaths from other causes. Here's a little bit what I learned about it at my College I go to.