Metadata

Metadata is data about data - information that describes the characteristics, context, and provenance of a dataset or data record. For a dataset, metadata includes the source system, collection date, schema version, record count, and refresh schedule. For an individual record, it might include a timestamp, source URL, or data quality score.

In API responses, metadata is typically returned alongside the payload - total result count, current page, request ID, and response time are all metadata that help clients interpret the data they receive. Good API design separates metadata from payload in the response envelope.

Metadata is the foundation of data catalogs, lineage tracking, and quality monitoring. Without metadata, you have data but no context - you cannot tell when it was collected, whether it is still fresh, or how it was processed. Capturing and maintaining metadata is a first-class concern in any data platform.