| The colorful pseudoscience|
|Hating thy neighbour|
|Divide and conquer|
The term ghetto is used to refer a poor and undeveloped part of a city where members of an oppressed minority group are forced to live, due either to brutal force used by totalitarian regimes, or by social and economic pressures in democratic society. The term originated in 16th century Venice, where Jewish people were segregated and lived in the Venetian Ghetto. Other cities in Europe formed segregated Jewish areas, and by the 19th century ghetto was the common term for these areas. After World War 2, the word ghetto became highly stigmatized due to the Nazi regime use of ghettos as concentration camps as part of the genocide of millions of Jewish people. Although Jewish segregation is no longer practiced, ghettos still exist today, in the United States, Europe, and worldwide, occupied by other marginalized groups.
The Venetian Ghetto was the first Jewish area where compulsory segregation was enforced to be called a "ghetto." It is commonly incorrectly believed it was the first segregated Jewish area. This is a misconception, as these areas had existed in Europe for three hundred years before. After WW2, the Venetian Ghetto was renamed because of Nazi associations of the word.
During WW2, the Nazis setup a system of mass discrimination against Jewish people and others deemed undesirable for racial reasons. Officially the Nazi ghettos were designated as Jewish Quarters, and Jewish people were forcibly relocated to the ghettos from other areas of Germany. This process of the "Ghettoization" of the Jews also took place in countries in which the Germans had gained military or political control, such as in Poland. 
There were several distinct types of Nazi ghettos, and they were used for different purposes in the Holocaust. Initially, the Germans organised "open ghettos", which despite the name were not fully open. This later moved to increased numbers of walled "closed ghettos", where escape was a capital offense. The final solution involved extermination camps, where Jewish people and others were murdered, and the eventual mass murder of almost all occupants of the Nazi ghettos in Operation Reinhard.