So what does metadata actually do?
Web pages often have metadata embedded in them. The links from one Web page to others and records of user behaviour—selecting individual pages to view from among lists of search results, for example—are types of metadata as well. Web search engines build up vast indexes that use page text and its attendant metadata to provide relevant search results to users.
Google goes even further. In 2012, it launched a knowledge base it calls the Knowledge Graph with 3.5 billion facts: metadata about 500 million people, places, and things, and the relationships between them. The Knowledge Graph and other structured metadata stored by Google are used to enhance search results and provide other value-added features such as sports scores, integration of search results with maps, and the knowledge cards that appear on the search results screen providing details on notable people and places.
Wikipedia, a free, crowdsourced online encyclopedia, both uses and generates metadata. The Wikimedia Foundation’s Wikidata project is an open and collaboratively edited knowledge base similar to Google’s Knowledge Graph. It stores factual information about topics in structured forms that can be pulled into Wikipedia articles or other information systems. The DBpedia project does the reverse, mining metadata from Wikipedia info boxes, categories, images, geospatial information, and links to generate an open resource of structured metadata that can be reused in countless ways.
Metadata is vital for business transactions, too. Retailers must track many details about the products they carry, including price, source, inventory quantity, and descriptive information. This is even more essential for online businesses; since online shoppers are unable to view items in person, they expect to be able to search by criteria such as keyword and object type, or to use facets to narrow a wide spectrum of products to a more manageable number.
Businesses routinely store metadata about searches and transactions, which enables them to analyze sales trends, predict future demand, pay sales taxes owed to governments, and more. This same metadata allows businesses to provide a more personalized shopping experience, with features such as purchase history, address books for multiple shipping locations, and product recommendations.
Manufacturers use metadata to track designs, parts, and materials, and to manage their research programs. The travel industry similarly relies on metadata about passengers, patrons, and bookings and about resources such as flights and hotel rooms.
News media use metadata to track events, coverage, and published content. All businesses use metadata for human-resource functions such as hiring, payroll, and performance management.
For the arts, metadata can be used for all of these purposes depending on need – discoverability, internal organization, providing technical information about your works, sales, and administration.