JSON-LD
JSON-LD, short for JSON for Linking Data, is a W3C standard serialization format for RDF: it lets ordinary JSON, the format most PHP applications already produce and consume, carry linked-data meaning by adding a small number of reserved keywords, most notably @context, which maps the document’s plain property names to globally unique URIs, and @id and @type, which identify a resource and its class. Because a JSON-LD document is still syntactically valid JSON, it can be parsed with json_decode() like any other payload, while tools built for linked data can additionally interpret it as a graph of RDF triples, expand or compact it against different contexts, or convert it to other RDF serializations such as Turtle or N-Quads. The lanthaler/JsonLD library provides a fully conforming JSON-LD processor implementing the official expansion, compaction, flattening, and framing algorithms, plus an object-oriented API for building and querying documents programmatically, and it is commonly paired with libraries like EasyRdf when a full RDF toolchain is needed. Its most common real-world use in web applications is embedding structured data inside a <script type="application/ld+json"> tag so that search engines and other crawlers can understand a page’s content, such as a product, an article, or an event, without needing to parse the visible HTML.
<?php
$document = (object) [
'@context' => 'https://schema.org',
'@type' => 'Article',
'headline' => 'Understanding JSON-LD',
'author' => (object) ['@type' => 'Person', 'name' => 'Ada Lovelace'],
];
echo json_encode($document, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
?>