Schema markup
Also called schema.org markup.
What Schema markup means
Schema markup is structured data written with the schema.org vocabulary, a shared set of types and properties maintained by a community project founded and sponsored by Google, Microsoft, Yahoo and Yandex. The vocabulary "can be used with many different encodings, including RDFa, Microdata and JSON-LD," and release 30.0 dates from 2026-03-19.
More precisely
Types range from Organization and Person to Article and DefinedTerm, each with its own properties and inherited ones. Some terms sit in the pending area at pending.schema.org, where schema.org labels the definitions provisional and subject to change. Three things are routinely conflated and are not the same: markup being valid, markup producing a documented rich result, and markup being used by an AI system.
Why it matters
Google states there is no special schema.org markup you need to add for generative AI search. A matched-control study of 1,885 pages that added JSON-LD between August 2025 and March 2026 reported changes in ChatGPT and AI Mode citations that were "statistically indistinguishable from zero," so markup is best justified by rich result eligibility and clarity rather than by citation gains.
Example
A glossary is modelled as a DefinedTermSet containing DefinedTerm entries, where `name` holds the term and `description` holds its definition.
Where this came from
Definitions here follow the specification or documentation that defines the term, not a paraphrase of another glossary.
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Schema.org — Schema.org
Schema.org is a collaborative community activity for structured data schemas, its vocabulary works with RDFa, Microdata and JSON-LD, and the live release is version 30.0 dated 2026-03-19.
Primary source · read 2026-09-03
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About Schema.org — Schema.org
Schema.org was founded and is sponsored by Google, Microsoft, Yahoo and Yandex, whose representatives sit on the steering group.
Primary source · read 2026-09-03
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We Tracked 1,885 Pages Adding Schema. AI Citations Barely Moved. — Ahrefs
A matched-control study of 1,885 pages adding JSON-LD against 4,000 control pages found effects on ChatGPT and AI Mode citations statistically indistinguishable from zero. Published 2026-05-11.
Primary source · read 2026-09-03
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Optimizing your website for generative AI features on Google Search — Google
Structured data is not required for generative AI search and there is no special schema.org markup to add for it.
Primary source · read 2026-09-03
developers.google.com/search/docs/fundamentals/ai-optimization-guide