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Technical implementation · Structured Data

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Definition

Web annotation is the practice of adding structured metadata or markup to web content to make its meaning and context explicit for AI systems and linked data applications. It encompasses schema.org markup, RDFa, JSON-LD, and other semantic enrichment techniques that convert plain web content into machine-interpretable data. Web annotation is the broader category that all structured data implementation belongs to. Every piece of schema markup, every sameAs link, every semantic HTML element is a form of web annotation — adding machine-readable meaning to content that would otherwise require AI systems to infer context from prose. A fully annotated entity page — with Organization schema, sameAs links, author schema, and semantic HTML — is maximally readable to AI crawlers.

Structured data

JSON-LD

RDFa

Linked data

Schema markup

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