Glossary
Universal semantic layer
Definition
A universal (or headless) semantic layer is a standalone semantic layer that sits between the data warehouse and many tools, so BI dashboards, spreadsheets and applications all share one set of business definitions.
What it means in practice
Universal semantic layers emerged to stop every BI tool from keeping its own copy of business logic. Definitions are typically written and maintained by data engineers in code or configuration files and exposed through SQL and APIs.
They are strong at consistency across BI tools. The trade-offs are the effort of modeling everything by hand and the fact that a single enterprise-wide model can struggle to capture how meaning differs between domains, which matters a lot once AI starts answering questions.
Example
Finance in Power BI and marketing in Tableau both query "gross margin" from the same universal semantic layer, so their reports match.