Mainly Jewish people were putted into Auschwitz but some Soviet POWs, Poles and Romas(Gypsies) were also putted into the Auschwitz camps.
About 17,000 at Auschwitz I, II and III combined.
You no doubt mean krematorium II and Krematorium III, which housed the largest gas chambers. They were not the only extemination complexes on Auschwitz, but they were where most people were killed.
Auschwitz II - that is the Birkenau section of the Auschwitz complex of camps - was a little over one square mile in area. It did not need to be enormous as, from March 1942 most new arrivals were gassed as soon as practical. Birkenau also housed the women's camp.
the stone and brick structures are left, but the wooden one (eg guard towers) are not. The ruins of krematoria II and III are also there, some wooden structures have been rebuilt, so that people can see what they were like.
Auschwitz I (or 1) was the original camp established in May 1940. It was an extremely harsh concentration camp, mainly for political prisoners - especially members of the Polish resistance. Auschwitz II (or 2, aka Birkenau) was begun in October 1941. It housed the extermination camp with the gas chambers and the women's camp as well as various other camps.
Auschwitz I Stammlager, Auschwitz II Birkenau and Auschwitz III Monowitz
Auschwitz Birkenau was established at Auschwitz but Auschwitz is now called Oświęcim.
Auschwitz I was the original Auschwitz camp, set up in May 1940, mainly for Polish political prisoners and the Polish elites. It also housed the main administrative offices for the whole complex of camps as well as the blocks where medical experiments were carried out, and execution chambers.
Auschwitz I- Birkenau
Auschwitz had 3 big 'main' camps. They were called Auschwitz I, Auschwitz Birkenau and Auschwitz Monowitz. Monowitz was really a sub camp which was commonly used and when expanded did become as part of the main camps. Out of the lot, Auschwitz Birkenau was the biggest and most feared of as this part was about Extermination when the Final Solution was putted in place.
It had 3 sections. Auschwitz-I, which served as a working camp. Auschwitz II-Birkenau, the death camp. Auschwitz-III, it was used to provide slave labor to the nearby industry.
From early 1942 Auschwitz operated as both. The only other camp that served as both a concentration camp and extermination camp was Majdanek.