JSON-LD is a JSON-based format for representing linked data, commonly used to publish structured data about a web page.
It matters because technical issues can prevent great content from being discovered, rendered, indexed, or trusted. Strong technical foundations protect rankings during redesigns, migrations, content expansion, and platform changes.
Example
A page can embed a JSON-LD object identifying the organization and its website using a script element with type application/ld+json. The content is structured JSON data, not executable JavaScript instructions.