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Metadata is data/information that provides data/information about other data. Metadata is essentially documentation of data.

There are three distinct types of metadata: descriptive metadata, structural metadata, and administrative metadata.

  1. Descriptive Metadata - describes a resource for purposes such as discovery and identification. It can include elements such as title, abstract, author, and keywords.
  2. Structural Metadata - is metadata about containers of data and indicates how compound objects are put together, for example, how pages are ordered to form chapters. It describes the types, versions, relationships and other characteristics of digital materials.
  3. Administrative Metadata - provides information to help manage a resource, such as when and how it was created, file type and other technical information, and who can access it.

Metadata is documentation that describes data.

Properly describing and documenting data allows users to understand and track important details of the work. Having said properly described and documented metadata about data facilitates search and retrieval of the data when deposited in a data repository/data silo/data warehouse.

Metadata is information about data. Similar to a library catalog record, metadata records document the who, what, when, where, how, and why of a data resource. Geospatial metadata describes maps, Geographic Information Systems (GIS) files, imagery, and other location-based data resources.

Metadata (meta data, or sometimes metainformation) is "data about other data", of any sort in any media. An item of metadata may describe an individual datum, or content item, or a collection of data including multiple content items and hierarchical levels, such as a database schema. In data processing, metadata provides information about, or documentation of, other data managed within an application or environment. This commonly defines the structure or schema of the primary data.

Why Do We Need Metadata?

Metadata are crucial for any potential use or reuse of data; no one can responsibly re-use or interpret data without accompanying metadata that explains how the dataset was created, why, where it is geographically located, and details about the structure and meaning of the data.

There are many uses for metadata, even beyond the simple discovery of datasets. Metadata can be used for understanding data, analysis and synthesis, maintaining longevity of a dataset for an organization, tracking the progress of a research project, and demonstrating the return on investment for research at an institution.

Key Points

  1. Data are not complete without a metadata record.
  2. Use metadata to understand and re-use data.
  3. Document everything about the data in the metadata record.
  4. Use mandated Federal metadata standards and tools to create metadata.
  5. Validate metadata to ensure they follow metadata standards.
  6. Share metadata with catalogs to improve discovery and access to the data.
  7. Metadata are an important component of a USGS data release.

For example, metadata would document data about data elements or attributes, (name, size, data type, etc) and data about records or data structures (length, fields, columns, etc) and data about data (where it is located, how it is associated, ownership, etc.). Metadata may include descriptive information about the context, quality and condition, or characteristics of the data. It may be recorded with high or low granularity.

The underlying concepts of metadata have been in use for as long as collections of information have been organized. For example, the information structure for materials in library card catalogs is a type of metadata that has served as a collection management and resource discovery tool for decades.

Metadata is essential for understanding information stored in data warehouses; using metadata makes it possible to create customizable elements for markup languages such as XML, HTML, XHTML, and SGML.

Metadata is machine understandable (read: machine readable) information for the web.

Metadata is such an imperative in data collection, entire data portals exist consisting solely of metadata about data, such as the City of Philadelphia's Benny the Metadata Catalog, and the Sunlight Foundation's Criminal Hall of Justice.

Core Components of a Metadata Record (According to FGDC)

Metadata Record Information - information about the metadata record including the language in which the record is written, a unique file identifier for the metadata record, the metadata standard used to organize the record, a point of contact for the metadata record, and the date that the metadata record written.

Identification Information – citation-level information about the data including the title, abstract, purpose for creation, status, keywords (theme and place), and extent (temporal, vertical and horizontal). Constraints Information – information about legal and security limitations to data access and use. Data Quality Information – information about the processes and sources used to develop the data and positional and/or accuracy assessments performed.

Constraints Information – information about legal and security limitations to data access and use. Data Quality Information – information about the processes and sources used to develop the data and positional and/or accuracy assessments performed.

Maintenance Information – information about the scope and frequency of data updates. Spatial Representation – information about the mechanism used to represent spatial data (grid, point, vector).

Reference System Information – information about the reference systems used to represent geographic position and time.

Content Information – information about the data set entities and attributes.

Symbology Information – information about the symbols used to represent spatial features.

Distribution Information – information about the data distributors and methods for obtaining the data.

Metadata Extension Information – information about custom, user-based, changes to the elements, domains or conditionality of the standard.

Application Schema Information – information about the schema or data models used to structure the data.

Citations, References and Resources for Metadata

Metadata - GIS Wiki
Geospatial Metadata -
Wikipedia Entry
Understanding Metadata - What is Metadata, and What is it For? (PDF)
Geospatial Metadata Fact Sheet - FGDC 2011-07 (PDF)
Metadata - USGS Data Management
FSP FAQ: Metadata for USGS Scientific Data
What is Metadata? - Indiana University Knowledge Base
Metadata and Resource Description - W3C
Metadata and Describing Data
Metadata Definition and Examples