Racism is based on the idea that there are different human races: the 'white race', the 'black race', the 'yellow race', and the 'red race'. People of the same race are assumed to share certain characteristics.
Hitler and the National Socialists (Nazis) also believed that people could be divided into races. And they believed that the races were in competition with each other. According to the Nazis, the Jews were a weak, dangerous, and inferior race that did not belong in Germany.
The ideas of Hitler and the Nazis were racist. After the Second World War, science showed that the classification of humanity into different races is wrong. There is only one race: the human race.