JSON-LD

JSON-LD is a JSON-based format for serialising Linked Data: it uses a context to map compact terms to identifiers and can describe entities, types, properties, and relationships in a machine-readable graph. On web pages, it is commonly used for Schema.org structured data inside a `<script type="application/ld+json">` data block in the document head or body. The block contains data rather than executable JavaScript.

Why it matters: For search markup, first choose a structured-data type supported by the intended consumer and make sure it accurately represents the page's primary visible content. Use the appropriate vocabulary and properties, stable identifiers where useful, valid JSON, and values that match what visitors can see. A JSON-LD block may appear in the head or body, and multiple connected entities can be expressed with nesting, identifiers, or `@graph`; avoid duplicate or conflicting records generated by themes, plugins, and application code. Treat dynamic values as untrusted when serialising them into HTML so they cannot break out of the data block. Validate the syntax and vocabulary, test the rendered page with the consumer's tools, and monitor processing reports after release. Google's preference for JSON-LD is an implementation recommendation, not evidence that the format itself improves ranking; valid markup only makes a page eligible for supported features and does not guarantee their display.