Auschwitz II (Birkenau) is the camp that people know simply as "Auschwitz". It was the site of imprisonment of hundreds of thousands, and the murder of over one million people, mainly Jews.
The camp's main purpose, however, was not internment with forced labor (as Auschwitz I & III) but rather extermination. For this purpose, the camp was equipped with 4 crematoria with gas chambers; each gas chamber was designed to hold up to 2500 people at one time.