Short Answer 
The Nazis forced Jewish populations into overcrowded ghettos after their conquest of Europe, particularly post-1939 in Poland, isolating them from society to control and oppress. Living conditions were horrific, marked by overcrowding, starvation, disease, and fear, leading many ghetto residents to be deported to concentration camps where they faced death. This systematic confinement was a significant aspect of the Holocaust, resulting in the murder of approximately six million Jews.
Step 1: Understanding the Implementation of Ghettos
Following their conquest of Europe, particularly after the invasion of Poland in 1939, the Nazis systematically forced Jewish populations into overcrowded ghettos. These ghettos were surrounded by walls or barbed wire and isolated Jewish residents from the rest of society. The purpose of this segregation was clear: to control and oppress the Jewish community.
Step 2: Living Conditions in the Ghettos
The ghettos were marked by incredibly horrific living conditions, as the Nazis provided limited resources and services to the inhabitants. Inside the ghettos, people faced severe issues, such as:
- Overcrowding, leading to a lack of privacy and space.
- Significant shortages of food and basic necessities, resulting in widespread starvation.
- Rapid spread of diseases due to unsanitary conditions.
- Constant fear and despair among residents.
Step 3: The Fate of Ghetto Residents
The ghettos served as a precursor to the eventual deportation to concentration camps. Many Jewish people from these ghettos were later taken to camps where they faced horrific treatment and, in many cases, death. This systematic confinement was an integral part of the broader oppression during the Holocaust, where approximately six million Jews were tragically murdered by the Nazi regime.