Stereotype: A generalized belief about a particular category of people. It's like an oversimplified mental picture that doesn't consider individual differences.
Discrimination: The unjust treatment of different categories of people, especially on the grounds of race, age, or sex. It's like choosing to only eat red apples because you believe they're superior to green ones, even though both are nutritious and tasty in their own ways.
Bias: An inclination towards one particular group, person, or ideology over another. It's like having a favorite football team and always cheering for them regardless of who they're playing against.