This card was stamped with the letter "J" which stands for Jude (Jew). All Jews had to have this identification card on them at all times because on July 23 1928 a decree was passed that all Jews where to apply for an identification card. A month later, another law was applied saying that all male Jews had to take the name "Israel" and all female Jews had to take the name "Sara".
Everywhere a Jewish person turned, the Nazis had the goal to humiliate and persecute then. On all buildings that a Jewish person resided in had a sign that read "In diesem Grundstuck wohnen Juden." They put this sign on the building because it told everyone who passed by that a Jewish person lived there. Because of this sign, many German people who were friends with Jewish people stopped going around the Jewish neighborhoods.