I just listened to a book called KL about the whole concentration camp system. It's a hard read (or listen, in my case) but very informative. I would say that almost no one in the US or beyond has any idea about how they were come about or why they were used. They were mostly for the purpose of eliminating opposition to the regime by frightening people (most were released at least early in KL system) or eventually killing them. Jews always got the hardest of treatment, but the main categories were communists, a-socials, criminals, Catholics, Jehovah's Witnesses, gypsys, Poles, and homosexuals. Once the war kicked off, the life in the KL got much worse and as the NAZIs gained more and more territory, the goal began to morph into complete destruction of Jewry. The mass killings really started in earnest in 43+/-, much later than mist people believe. Many in Auschwitz, for example, belonged to the categories I mentioned earlier. The only Jews that were (late in the war, at least) there were saved because they were strong enough to work. The elderly, infirm, and Women with children were typically sent straight to the killing centers and not even registered in the camp. I realize there is a lot of generalization in the last paragraph, but there were enough exceptions to things, to make a "short" synopsis incredibly difficult to get right. It's well within the ball park, however.