The background of The Holocaust

The Holocaust, the extermination of Jews and executed by Nazi regime under the leader Adolf Hitler. The persecution and genocide were accomplished in stages. Legislation to remove the Jews from civil society was enacted years before the outbreak of World War II. Concentration camps were established in which inmates were used as slave labors until they died of exhaustion or disease. Jews and Roma were crammed into ghettos before being transported hundreds of miles by freight train to extermination camps where, if they survived the journey, the majority of them were killed in gas chambers. Every arm of Germany's bureaucracy was involved in the logistics of the mass murder, turning the country into what one Holocaust scholar has called "a genocidal state.
Leading up to the 1933 elections, the Nazis began intensifying acts of violence to wreak havoc among the opposition. With the cooperation of local authorities, they set up camps as concentration centers within Germany. These early prisons—usually basements and storehouses—were eventually consolidated into full-blown, centrally run camps outside the cities. By 1942, six large extermination camps had been established in Nazi-occupied Poland. After 1939, the camps increasingly became places where Jews and POWs were killed or forced to live as slave laborers, undernourished and tortured. It is estimated that the Germans established 15,000 camps in the occupied countries, many of them in Poland. The transportation of prisoners was often carried out under horrifying conditions using rail freight cars, in which many died before reaching their destination.
Extermination through labour, a means whereby camp inmates would literally be worked to death—or frequently worked until they could no longer perform work tasks, followed by their selection for extermination—was invoked as a further systematic extermination policy. Furthermore, while not designed as a method for systematic extermination, many camp prisoners died because of harsh overall conditions or from executions carried out on a whim after being allowed to live for days or months.
After the invasion of Poland, the Nazis established ghettos throughout 1941 and 1942 to which Jews and some Roma were confined, until they were eventually shipped to death camps and killed. They were, in effect, immensely crowded prisons, described by Michael Berenbaum as instruments of "slow, passive murder. From 1940 through 1942, starvation and disease, especially typhoid, killed hundreds of thousands. Over 43,000 residents of the Warsaw ghetto died there in 1941.
Each ghetto was run by a Judenrat (Jewish council) of German-appointed Jewish community leaders, who were responsible for the day-to-day running of the ghetto, including the provision of food, water, heat, medicine, and shelter, and who were also expected to make arrangements for deportations to extermination camps.

by Victor
References:
“The Holocaust”, from Wikipedia, the free encyclopedia.