In 1942, the Holocaust (shooting of Jews) was replaced by new method, gassing. Nazis had used concentration camps to hold their enemies, these were "death camps", where Jews would be killed.
All six camps were built in Poland, located in good rail links and relative isolation. Jews from countries all over Europe were rounded up, sent there by train and gassed to death.
In the camp, they had to remove their luggage, coats, shoes, and whatever they're wearing and once they're undressed, they were led into the ravine.
When they reached the bottom they were seized by members of Schutzpolizei and madde to lie down on top of Jews that had been shot in layers. A police marksman came and shot each Jews.
Every morning, they had woken up to attend roll call. They had to go outside and line up. They had to stand like this until every single inmate of the camo had been counted. This included all those who died during the night. They had to do the same like this even if it's winter.
Another method of killing the Jews is the Gas chambers. The Nazis had made an improvement on this camp to made over Treblinka (Holocaust). Gas chambers accommodate 2,000 people at one time. There were two SS doctors on duty at Auschwitz to examine the incoming transports of prisoners.