Schema.org is a collaborative vocabulary for structured data on the web, maintained jointly by Google, Microsoft, Yahoo, and Yandex since 2011. It provides a shared set of types (like Article, Person, DefinedTerm) and properties (like author, datePublished, description) that web pages use to describe their content in machine-readable form.
How it works
Schema.org defines a type hierarchy. Thing is the root. Below it sit types like CreativeWork (which includes Article, Book, LearningResource), Person, Organization, and Place. Each type has properties that describe instances of that type.
The vocabulary is designed to be broad enough for general use while specific enough to be useful. A DefinedTerm has a name, a description, and an inDefinedTermSet. An Article has a headline, author, datePublished, and articleBody.
Encoding
Schema.org types are used with one of three encoding formats:
- JSON-LD (recommended)
- Microdata
- RDFa
The vocabulary is the same regardless of encoding. Schema.org defines what to say; the format defines how to say it.
Relevance
Schema.org is the de facto standard for communicating page semantics to search engines and AI systems. When a page declares itself a DefinedTerm, search engines can surface it in response to definitional queries. When a page declares itself a LearningResource, educational search tools can index it appropriately.
See also: structured data, JSON-LD.