Machine learning is useful for fraud detection in banks by examining transaction patterns and comparing them to known fraudulent activity to identify potential fraud. It uses algorithms trained on historical data to spot these patterns and predict fraudulent transactions. However, machine learning models must be constantly updated with new information as fraud patterns change over time. It can help banks prevent fraud even when unauthorized access is not attempted by flagging suspicious behavior for human review. The benefits of machine learning for fraud detection include increased speed, efficiency, and accuracy compared to traditional methods.