The second were the transit camps, which served as concentration points in the Nazi-occupied countries, from which trains transported the inmates to either labor or death camps further east.
The last to be established were the death camps, of which Sobibor is an example. These camps were not built until 1942, and were designed specifically for killing on a mass scale. Most were located in Poland.
Sobibor, in the Lublin district of Poland, opened in May 1942. Most of the Dutch Jewish population that suffered deportation to the camps were sent to either Auschwitz or Sobibor. Before it closed, an estimated 250,000 Dutch, French, and Polish Jews were murdered there.