Everything you need to know about the Holocaust is contained in this official Jewish version: https://www.thoughtco.com/holocaust-facts-1779663
The following quote is from the official Jewish version:
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Concentration and Extermination Camps
Although many people refer to all Nazi camps as concentration camps, there were actually a number of different kinds of camps, including concentration camps, extermination camps, labor camps, prisoner-of-war camps, and transit camps. One of the first concentration camps was in Dachau, in southern Germany. It opened on March 20, 1933.
From 1933 until 1938, most of the people held in concentration camps were political prisoners and people the Nazis labeled as “asocial.” These included the disabled, the homeless, and the mentally ill. After Kristallnacht in 1938, the persecution of Jews became more organized. This led to the exponential increase in the number of Jews sent to concentration camps.
Life within Nazi concentration camps was horrible. Prisoners were forced to do hard physical labor and given little food. Prisoners slept three or more to a crowded wooden bunk; bedding was unheard of.
Torture within the concentration camps was common and deaths were frequent. At a number of concentration camps, Nazi doctors conducted medical experiments on prisoners against their will.
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