Prejudice is the unsubstantiated prejudgement of an individual or group, favourable or unfavourable in character, tending to action in a consonant direction. Even favourable prejudices should be discouraged since they too represent unwarranted generalizations, mostly of an irrational nature. Although prejudice may apply to objects as disparate as trade-union leaders, women, or exotic foods, in practice it has been considered as dealing primarily with populations or ethnic groups distinguished by the possession of specific inherited physical characteristics (race or sex), or by differences in language, religion, culture, national origin, or any combination of these.
There are two types of people: those who divide people into two types, and those who don't.
"Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence." (Albert Einstein).
Prejudgements are normal and common because perception and cognition require the placing of particular items into more general categories. As long as the prejudgement is adjusted to correspond with reality no harm is done, and the process of thinking may be made more efficient.