Some like the dry definition of metadata as 'data about data,' but it has more value when thought of as a form of storytelling best told through controlled dictionaries, vocabularies, glossaries, thesauri, hierarchies, taxonomies, folksonomies, ontologies, and knowledge graphs.

Operational metadata

Profiles data or data content for determining what the data can be used for. Powers the data lifecycle process for assessing where to store and how long to keep the data (hot, warm, cold).

Used for Identification (terms, languages, author, subject, keyword, title, publisher, type, definition), Quality, Validation, Reliability, Lineage (provenance), and Metrics (freshness, duplicates)

Structural metadata

Data about the containers of data; order/organization information, like page order, tables, columns, keys, indexes, and relationships.

Administrative metadata

Information describing Rights Management (intellectual property, ownership, source, access, digital rights, privacy) and Preservation (created date, file type, file version, and retention)

Business process metadata

Models and rules.