During the Second World War (in 1938) Hitler begins to introduce racial laws against the people of Jewish origin. These laws originally prohibited Jews from shopping in stores, going to school, teaching, and practicing any sport or job. Jews over the age of 6 in the areas occupied by Germany, were forced to wear the star of David with the word jude, in front of and behind their clothing.
In October 1939 the first ghetto was built in Poland, that is a small neighborhood enclosed by a wall where Jews were separated from non-Jews, many Jews there died of disease or starvation. Often the ghettos were just a transit point because from there the Jews were then deported to extermination camps such as that of Auschwitz.
The Nazis often deported Jews with trains but it also happened that they deported them with vans or ships, in the wagons of locomotives they died even before they reached the extermination camps. In the concentration camps Jews were often killed in gas chambers or in various other ways.
In 1945 the Germans were finally defeated by the Russians who freed the Jews (now few of them left).
We must remember what has happened to ensure that it never happens again.