[JSON-LD](https://json-ld.org/) is a JSON-based linked data format that defines
the concept of `context` to specify the vocabulary for types and properties.
Gmail supports
[JSON-LD data embedded in HTML documents](https://json-ld.org/spec/latest/json-ld/#embedding-json-ld-in-html-documents)
with the `@context` of `schema.org`, as in the following example:

    <script type="application/ld+json">
    {
      "@context": "http://schema.org",
      "@type": "Person",
      "name": "John Doe",
      "jobTitle": "Graduate research assistant",
      "affiliation": "University of Dreams",
      "additionalName": "Johnny",
      "url": "http://www.example.com",
      "address": {
        "@type": "PostalAddress",
        "streetAddress": "1234 Peach Drive",
        "addressLocality": "Wonderland",
        "addressRegion": "Georgia"
      }
    }
    </script>

**Note** : The `@type` key is a reserved key name and should contain either a full
type URI or a URI fragment (in which case an `http://schema.org/` prefix,
derived from the supplied data-context attribute, is assumed).

For the full specifications and requirements for the JSON-LD syntax, see
[json-ld.org](https://json-ld.org/). You can also
[test your schemas](https://developers.google.com/workspace/gmail/markup/testing-your-schema) to try out
JSON-LD and debug your markup.