The word “prejudice” comes from pre/judge, i.e. to make a definite preliminary judgment about a person or group of people without having sufficient knowledge to assess the situation. 

The fact of having prejudices about someone is based on stereotypes. 

Prejudice is a socially learned preconception, shared by members of a group. In everyday language, the word is used to describe a negative, unfavorable or even hostile attitude towards people who have been reduced to a general category.

Examples of prejudices: hostility and blame towards working-class or poor people; hostile attitudes toward the elderly; hostility toward economic migrants and refugees.