# Data catalog

> A searchable inventory of an organization's datasets, with what each one means.

- Level: Intermediate
- Topics: Data
- URL: https://tidbit.legios.com.ar/data-catalog/
- In Spanish: [Catálogo de datos](https://tidbit.legios.com.ar/es/data-catalog/)

A **data catalog** is an inventory of the data an organization has: every table, file and dashboard, with a description of what it contains, who owns it, when it was last updated and how it connects to the rest. It does not hold the data itself; it holds metadata about it and points to where the data lives.

The everyday use is search. An analyst who needs "monthly revenue by country" types it into the catalog and finds the right table in the data warehouse, sees that the `amount` column is in dollars and excludes refunds, and knows who to ask if something looks off. Many catalogs also show **lineage**: which jobs produced a table and which reports depend on it.

Catalogs exist because data grows faster than anyone's memory. In a data lake with thousands of folders, a file that nobody can find or understand is as good as gone. Tools such as AWS Glue Data Catalog, Google's Dataplex, Unity Catalog or the open source DataHub fill this role, and the catalog is usually where data governance rules become visible to everyone.

## An analogy

A library catalog: you do not walk every shelf looking for a book, you search the catalog, read the card with the author, the topic and the shelf number, and then go straight to it.

## Keep in mind

- Lists datasets with descriptions, owners, columns and freshness.
- Stores metadata and pointers, not the data itself.
- Lineage shows where a table comes from and what depends on it.
- Keeps a data lake from turning into a swamp.

## Go deeper

- [What is a data catalog? (AWS)](https://aws.amazon.com/what-is/data-catalog/)
- [Data catalog on Wikipedia](https://en.wikipedia.org/wiki/Data_catalog)
- [What is a data catalog? (IBM)](https://www.ibm.com/think/topics/data-catalog)

## Related terms

- [Metadata](https://tidbit.legios.com.ar/metadata/): Data that describes other data: who made it, when, where and what it contains.
- [Data warehouse](https://tidbit.legios.com.ar/data-warehouse/): A database built for analysis: years of history, from many sources, in one place.
- [Data lake](https://tidbit.legios.com.ar/data-lake/): Cheap storage where all your data is kept as raw files, to be sorted out later.
- [AWS Glue](https://tidbit.legios.com.ar/aws-glue/): AWS's service for finding, describing and cleaning up data, with no servers to run.
- [Google](https://tidbit.legios.com.ar/google/): The search company that gives most products away and makes its money on ads.
- [Open source](https://tidbit.legios.com.ar/open-source/): Software whose code anyone can read, use, change and share.
- [Data governance](https://tidbit.legios.com.ar/data-governance/): The rules and roles that decide who owns data, who can use it and how it is kept right.