Nazi Germany built and operated a system of concentration camps between 1933 and 1945. In these camps, prisoners were held in inhumane conditions, with the majority of prisoners dying from causes including disease, malnutrition, forced labor, maltreatment and execution by their captors. There were more than a thousand such camps, including subcamps in Germany and German-occupied Europe. In addition to the concentration camps, there were several other kinds of internment camps, and from 1941 onward an associated system of extermination camps was created that was dedicated solely to the systematic murder of millions of people. Millions of other victims of Nazi Germany were also killed in places outside the concentration camp system.