Try to make a fundamental and common definition of "prejudice": it's an opinion, of course, favorable or unfavorable (more often the latter!). Many times, it's an opinion formed without fair examination of facts. Prejudice creates biases, bad influences, and inquiries.
Prejudice can become dangerous if it is spread on a large scale. In media such as newspapers, tv, or radio, for instance. Or on social media.
A possible correction afterwards is seldom given or will be even rejected. Very often prejudices become coarse, rude and gross generally.
Prejudices that involve negative stereotypes of others, particularly identifiable groups, can undermine the self-esteem of persons in those groups and also deprive them of opportunities that require positive assessments of their abilities and behaviors.
In all parts of our globe, we find an ethical hierarchy. It's an indirect status with fixed judgement and points of view. Social distance and discrimination predominate and make it easier to use categories such as "race", "nation" or "culture". Social differences have been built up.
Gays and lesbians are "unnatural" (?), all black people are "dirty" (?), all white people are "rich"? - Heaven forbid! But I experienced it myself many times: I stayed in Israel sometime in 1978 and was not really welcomed by the people, because of my"Nazi-roots" (though I was born 1953!). Later, I was rejected from the Golan Heights, because I came from (enemy!) Israeli territory. Staying in South Africa sometime in 1980, I experienced the terrible racism and fascism of the former apartheid government and its painful effects and consequences. Yes, I mentioned such things already earlier in the corner.
Most racial prejudices have its roots from the heritage of colonial supremacy. Justification of slavery goes back to the 17th century. In early colonial history skin color was not the main reason, it was the paganism of original inhabitants in America, Africa, and Australia.
Terms such as "Indian" and "Negro" can be even found in the literature: the good-natured Indian variant "Winnetou" (Karl May, 1842-1912, Germany) or "Friday" (Freitag), the noble savage in "Robinson Crusoe" (Daniel Defoe, 1660-1731, England), or how about "Uncle Tom" (Harriet Beecher-Stowe, 1811-1896, USA).
Political conflicts between "white colonial supremacies" and "coloured subjects" have been explained and described as racial segregation - many times instigated by Christian missionaries. Innumerable examples in world history proved brutal force and power up to genocide.
Prejudices? "Love your neighbour as yourself!" (Leviticus 19:18). "When an alien lives beside you in your land, do not mistreat him. The alien living with you must be treated as one of your native-born!" (Leviticus 19:33,34). Integration, ecumenical movements, support of especially discriminated and disadvantaged groups are keynotes for the future. They should be!
Bias and prejudice, or simply ignorance, can lead to isolation, vulnerability, disadvantage and discrimination at school, at work, in stores and other services, or even where people live.
The "stranger in media" or "the strangeness - a feigned difficult standard" ... we could really really live together easier and more respectful of each other. Let's honour each other more in future. If there is a will, there is also a way!