The auditor's answer to "how big does a mistake have to be before anyone cares?" Amounts below the materiality threshold are too small to change any decision; amounts above it demand attention. Standards like AICPA AU-C 320 and ISA 320 define how it's set.
In Bizdivers: the Internal Assessment module uses configurable overall and performance materiality to decide what gets flagged, so you review what matters instead of everything. See Your books, continuously audited.