Definition
Schema Markup (Structured Data)
Schema markup (structured data) is Schema.org code that tells engines explicitly what a page is, an organization, product, article or FAQ, instead of making them infer it from prose. It's usually added as JSON-LD.
Removing that ambiguity makes your content easier to understand, trust and cite correctly. Guide: why structured data matters for AI visibility.
What format should schema markup use?
JSON-LD is the recommended format, a script block in the page's HTML that engines and search crawlers most reliably parse.