Operational Loss Data comprises detailed records of loss events including financial impact, event type, business line, root cause, and recovery amount, used to identify trends, calibrate risk models, and satisfy regulatory requirements. Basel III requires banks to maintain at least five years of internal loss data for operational risk capital calculations. Organizations categorize losses using standardized taxonomies (fraud, systems failures, process errors, external events) to enable benchmarking against industry consortia. For example, analyzing transaction processing errors might reveal that 80% of losses stem from manual reconciliation failures, justifying automation investment and providing data for scenario analysis of future loss distributions.