What is the ROC AUC metric?

ROC AUC (Receiver Operating Characteristic - Area Under Curve) is a metric for the quality of binary classification, measuring the model's ability to distinguish classes. The ROC curve plots True Positive Rate (sensitivity) against False Positive Rate (1 - specificity) at various classification thresholds. The AUC value — the area under this curve — ranges from 0 to 1. The closer AUC is to 1, the better the model separates positive and negative classes. A value of 0.5 corresponds to random guessing.