An individual measurable property of data used as input to a model (e.g., age, location, purchase history, medical codes). Feature choice affects model behavior; in regulated contexts, using protected characteristics (or close proxies) as features may trigger heightened review or restrictions depending on the use case and jurisdiction. In older models, features were frequently chosen by data scientists; in modern large models, features are usually discovered as part of the training process and may not be explicit.
See: Bias; Feature engineering; Training data