Bias refers to a preference or inclination towards a specific individual, group, or idea. It means having a tendency to like or dislike certain things or people without considering objective facts or proof.
For example, if a teacher consistently gives higher grades to students who participate in class discussions, that teacher may be displaying bias either in favor of more talkative students or against quieter students.
Very Simple Definition:
Bias means preferring one thing or person over another without a good reason.
For example, if a teacher always gives better grades to students who talk a lot in class, that is bias.