AI bias is when the system treats people or cases unfairly because the examples it learned from were skewed. If past hiring favored one background, a screening tool will favor it too. The system does not know it is unfair. It is copying the pattern it was shown.
This is a business and a legal problem, not a technical footnote. Look at outcomes by group for any decision that affects a person's job, credit, care, or access. If you would not defend the pattern to those people, do not automate it. Sometimes the right move is to leave the decision with a person.
Think of it this way: If every example of 'a good candidate' in your training data was a 45-year-old man, the model learns that pattern, not what actually makes a candidate qualified.
A lending company deploys a credit scoring model that inadvertently penalizes applicants from certain postal codes. The pattern existed in historical data; the model amplified it into a discriminatory outcome.
A lender's model declined a higher share of applications from one postcode. The postcode had stood in for income in the old data. Once the team saw the decline rates side by side, they removed the postcode and reviewed the declines that had used it. The gap was the audit, not a surprise in the math.
Bias testing is mandatory before deploying any AI used in hiring, lending, healthcare, or any decision that affects people differently based on protected characteristics. Bias is not a hypothetical risk to address after launch. Do not deploy high-stakes AI in people-affecting decisions without documented fairness testing and ongoing monitoring in place.
RaftLabs treats this as part of the build: a source on the answer, a test set, and a record of what the system did. The launch is the start of that work, not the end. The related work on our side is AI governance.
This sits with the other reliability & risk terms on the glossary. Why a confident answer can still be wrong, and how you catch it. Worth reading next: Hallucination, Guardrails, and Evaluation (evals).