Precision
Of all the times a model said 'yes,' the share that were actually right. High precision means few false alarms.
Think of It Like This
A smoke detector with high precision rarely goes off just for burnt toast.
Precision is true positives divided by all positive predictions, so it directly punishes false positives. It matters most when acting on a wrong "yes" is costly — flagging a legitimate transaction as fraud, say, and freezing a customer's card. It's almost always read alongside recall, because you can game precision to near-perfect just by predicting "yes" only when you're absolutely certain.