DAX (Data Analysis Expressions) is the formula language used in Microsoft Power BI to create measures, calculated columns, and business logic inside semantic models. It looks similar to spreadsheet formulas, but it is designed for data models, filters, and relationships rather than cell-by-cell editing.
DAX matters in cyber security because BI formulas can influence what users see, how totals are calculated, and which records are included in a report. Weakly written DAX can expose sensitive data through incorrect filtering or inconsistent row-level logic, while well-designed DAX helps centralize calculations and make them easier to review. In real environments, security teams look at DAX alongside permissions, sensitivity labels, and access controls to ensure reports do not leak information or bypass governance rules.