A catalog is a search engine for your own data. It answers the two questions that otherwise consume analyst time — does a dataset for this already exist, and can I trust it — by putting technical structure, business definitions and ownership in one place. Most catalogs can harvest structure automatically from warehouses, BI tools and pipelines; none can supply meaning, which is why a catalog is a governance project wearing a tooling budget.
In practice. Catalog adoption tracks a single number: the share of assets people actually search for that have an owner and a definition. Populating the top 200 assets well beats populating 20,000 emptily, and it is the version that gets used twice.
Where it goes wrong. The catalog is bought before the definitions exist and rolled out as the program's deliverable. Six months later it holds every column in the estate, 3% have a description, and the organization concludes that catalogs do not work. The tool worked fine; there was nothing to put in it.