Metadata is data about data. In a data warehousing environment, there are two types of metadata -- technical and business. Technical metadata describes data elements as they exist in the source systems, the data warehouse, and the interim data staging areas. Technical metadata also includes specifications on how the data is extracted, transformed, cleansed, and aggregated at each stage and the schedules for the data warehouse processes that accomplish this. This metadata is used by data warehouse administrators, power users, and the tools that drive the processes of the data warehouse.

In contrast, business metadata is used by business users and by decision-support tools. The information is related to the technical metadata, but the presentation is very different. Business metadata provides a subject-oriented view of data. It describes data objects like databases, tables, and columns, as well as informational objects like queries, charts, and reports. The metadata also contains the business dimensions, hierarchies, and formulas needed by business users to simplify their query and data navigation, and support more in-depth analysis.