JSON-LD
Also known as: JavaScript Object Notation for Linked Data
In short
A JSON-based format for expressing linked data, using a context to connect property names and values to shared meanings.
Separate the format from the vocabulary
JSON-LD expresses structured relationships in JSON. A context maps short terms to identifiers so different systems can interpret them consistently. Common keywords include @context, @type and @id.
An e-commerce page often uses JSON-LD with Schema.org vocabulary. The format carries the data; the vocabulary describes concepts such as Product and Offer. An ordinary JSON object does not become JSON-LD merely because its fields contain product information.
On a web page, JSON-LD is commonly embedded in a script element with the type application/ld+json. It describes content for machines and does not create the visible product interface.
Illustrative example
Imagine a product page that publishes a JSON-LD record for a desk lamp. Its context identifies Schema.org, its type identifies a product, and an offer supplies the displayed price and currency.
The same catalog can supply both the visible page and the structured record. This reduces the risk that one says the lamp is available while the other says it is sold out.
Validate meaning as well as syntax
A parser accepting the JSON proves only part of the work. Check entity relationships, supported properties and the consuming service’s requirements. JSON-LD is not automatically an advertising feed, and valid markup does not guarantee a particular search appearance.