JSON-LD

What it is

JSON-LD is a JSON-based serialisation for embedding Schema.org structured data, placed in a script block rather than woven into visible HTML. It expresses entities and their relationships as linked data that machines can parse independently of page layout.

Why it matters

Its separation from the rendered DOM makes facts easier and cheaper for crawlers and LLMs to extract reliably, and it is the format generative systems increasingly favour when retrieving structured facts.

How it works

You declare a context and type, then list properties as key value pairs, often linking nodes by @id so that entities reference one another across the same page or site.

When it applies

It applies to any page where you want structured facts represented cleanly and decoupled from presentation markup.

Examples

• A script type application ld plus json block in the head describing an Organisation
• Linking an Article node to its author Person node via a shared @id
• A FAQPage block listing question and answer pairs as structured nodes

How it is measured

• JSON-LD parses as valid JSON and as valid linked data
• Entities correctly cross-reference via @id without dangling references
• Consistency between JSON-LD claims and the visible on-page content
• Share of structured data delivered as JSON-LD versus microdata or RDFa