Metadata

Metadata are data about data. More specifically within geography, they consist of digital background information about the origins of geospatial data. The data metadata describe are not necessarily limited to purely electronic data sets but can involve various formats and media. As standard operating procedure within geographic information systems (GIS), metadata play an essential role in identifying data usability and accessibility. A lack of metadata renders a data set less useful or even useless in analysis, since its legitimacy cannot be ensured. The following describes the content, format, standards, uses, and importance of metadata in geography.

Metadata accompany geospatial data in a separate file that includes pertinent information about the data set. The content is designed to allow for situational evaluation of data usability. This record consists of basic identification, quality, spatial reference, organization, attribute, acquisition, and proper usage information on a data set. Common examples of this content are title, author, contact information, equipment used, processing history, update plan, purpose, rights of use, and geographic projection. Metadata also include the author and currency of the metadata themselves.

The content of metadata follows international (International Organization for Standardization, ISO) or national (Federal Geographic Data Committee, FGDC) standards. These standards specify the different types of information that should be present but do not dictate organizational or transfer protocol. The format for metadata is Extensible Markup Language (XML) or Standardized Generalized Markup Language (SGML), although it can also be a word-processing document, in Hypertext Markup Language (HTML), in Portable Document Format (PDF), or a text file, so long as it accompanies the data.

Organizations use metadata to maintain internal data management standards, to plan spatial data updates and acquisitions, to keep a data inventory for data clearinghouses, and to facilitate spatial data transfer and proper interpretation. They implement metadata to set priorities and maintain data quality and consistency. Metadata can also optimize communication between organizations through a common platform for discussing and documenting data.

Within geography, the importance of metadata rises above that of simple organization, since spatial data sets are incorporated into analysis and decision making. Considering the exponential growth of GIS data availability, there needs to be a mechanism for sorting and evaluating such data prior to acquisition and usage. Metadata maintenance is essential for spatial data management and documentation. This documentation facilitates data location, acquisition, interpretation, and implementation. It provides a clear indicator of the accuracy and currency of data and the legality of data usage. It also identifies the original purpose and scale of the data so that proper incorporation of metadata into mapmaking and decision making can minimize inaccuracy and bias. Metadata play a vital role in geography by providing a common language for geospatial data set interoperation, thus ensuring timeliness and accuracy.