The Nazi preoccupation with racial purity ultimately led to the systematic and deliberate mass murder of European Jews. The vast majority of European Jews were murdered after 1941 in what was called the Final Solution.
Not every camp in Nazi territory was a death camp- many acted as a combination of labor, deportation, transit, and death camps. The Nazi government implemented Operation Reinhard named after Reinhard Heydrich, who convened the Wannsee Conference and implemented the Final Solution (and who was assassinated by Czech partisans in Prague,1942).
Operation Reinhard death camps included the notorious killing centers of Belzec, Sobibor, and Treblinka. These camps existed between 1942 and 1943, and together killed an estimated 1.7 million people.