A business glossary is a repository of business terms and rules relevant to your company. These terms can then “explain” data in the data catalog or give context to what the data or specific terms are referring to.
What the term “Active Customer” means and how it is calculated would be stored in the business glossary (e.g., how much activity constitutes “active,” can employees be active customers, etc.)
The business glossary can exist as an essential part of your data catalog. As the primary tool for locating and organizing data, the data catalog will need these terms and their related information to aid users in search and analysis. Data stewards or business users will populate the business glossary with relevant terms because they understand both the technical and business aspects of the organization’s data.
Business glossaries are essential because, depending on your users’ expertise, they can rely on data for different reasons (and therefore, their definitions of key terms can differ). They need to link that data to universally understood business terms to explain what specific data means to end users. You should also link your business glossary to external applications (like business intelligence tools) to prevent confusion outside the catalog.
A comprehensive glossary will decrease your organization's number of questions and back-and-forth debates. Whether there is a dispute about definitions of business terms, the meaning of data in unknown attributes, how a particular report was filtered, etc. – the answer is always in the business glossary.