Bias is a tendency to favor or oppose something in a way that isn't fair or balanced. When you have a bias, you lean toward one side before looking at all the evidence, like a judge who's already decided who should win before hearing both sides of the case.

Everyone has biases, often without realizing it. A teacher with a bias might call on boys more than girls, or assume the quietest student in class isn't paying attention. A news reporter with a bias might describe the same event differently depending on which side they favor. Your own brain might have a bias toward believing your best friend's version of an argument, even before you hear what the other person has to say.

Biases can be subtle. You might have a bias toward choosing chocolate ice cream, which is harmless. But biases become serious problems when they affect how we treat people or make important decisions. Someone with a bias against left-handed people might unfairly assume they're clumsy. A hiring manager with a bias might reject qualified job applicants based on irrelevant factors.

People handle bias by recognizing it exists. Scientists design experiments carefully to avoid bias in their results. Good thinkers try to spot their own biases and correct them. When someone catches themselves making a snap judgment, asking “Am I being fair, or do I have a bias here?” is a smart first step.

As a verb, bias means to influence someone unfairly, or to make something lean in a particular direction. For example, a leading question can bias a survey, and a personal grudge can bias a decision.