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<!DOCTYPE html>
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<title>JSON-LD 1.1</title>
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<body>
<section id="abstract">
<p>JSON is a useful data serialization and messaging format.
This specification defines JSON-LD 1.1, a JSON-based format to serialize
Linked Data. The syntax is designed to easily integrate into deployed
systems that already use JSON, and provides a smooth upgrade path from
JSON to JSON-LD.
It is primarily intended to be a way to use Linked Data in Web-based
programming environments, to build interoperable Web services, and to
store Linked Data in JSON-based storage engines.</p>
<p>This specification describes a superset of the features defined in
[[[JSON-LD10]]] [[JSON-LD10]]
and, except where noted,
documents created using the 1.0 version of this specification remain compatible with JSON-LD 1.1.</p>
</section>
<section id="sotd">
<p>This document has been developed by the
<a href="https://www.w3.org/2018/json-ld-wg/">JSON-LD Working Group</a> and was derived from the <a href="https://www.w3.org/community/json-ld/">JSON-LD Community Group's</a> <a href="https://www.w3.org/2018/jsonld-cg-reports/json-ld/">Final Report</a>.</p>
<p>There is a
<a href="https://json-ld.org/playground/">live JSON-LD playground</a> that is capable
of demonstrating the features described in this document.</p>
<p>This specification is intended to <a href='https://www.w3.org/2019/Process-20190301/#rec-rescind'>supersede</a> the [[[JSON-LD10]]] [[JSON-LD10]] specification. </p>
<section>
<h2>Set of Documents</h2>
<p>This document is one of three JSON-LD 1.1 Recommendations produced by the
<a href="https://www.w3.org/2018/json-ld-wg/">JSON-LD Working Group</a>:</p>
<ul>
<li><a href="">JSON-LD 1.1</a></li>
<li>[[[JSON-LD11-API]]]</li>
<li>[[[JSON-LD11-FRAMING]]]</li>
</ul>
</section>
</section>
<section class="informative">
<h1>Introduction</h1>
<p>Linked Data [[LINKED-DATA]] is a way to create a network of
standards-based machine interpretable data across different documents and
Web sites. It allows an application to start at one piece of Linked Data,
and follow embedded links to other pieces of Linked Data that are hosted on
different sites across the Web.</p>
<p>JSON-LD is a lightweight syntax to serialize Linked Data in
JSON [[RFC8259]]. Its design allows existing JSON to be interpreted as
Linked Data with minimal changes. JSON-LD is primarily intended to be a
way to use Linked Data in Web-based programming environments, to build
interoperable Web services, and to store Linked Data in JSON-based storage engines. Since
JSON-LD is 100% compatible with JSON, the large number of JSON parsers and libraries
available today can be reused. In addition to all the features JSON provides,
JSON-LD introduces:</p>
<ul>
<li>a universal identifier mechanism for <a>JSON objects</a>
via the use of <a>IRIs</a>,</li>
<li>a way to disambiguate keys shared among different JSON documents by mapping
them to <a>IRIs</a> via a <a>context</a>,</li>
<li>a mechanism in which a value in a <a>JSON object</a> may refer
to a <a>resource</a> on a different site on the Web,</li>
<li>the ability to annotate <a>strings</a> with their language,</li>
<li>a way to associate datatypes with values such as dates and times,</li>
<li>and a facility to express one or more directed graphs, such as a social
network, in a single document.</li>
</ul>
<p>JSON-LD is designed to be usable directly as JSON, with no knowledge of RDF
[[RDF11-CONCEPTS]]. It is also designed to be usable as RDF
in conjunction with other Linked Data technologies like SPARQL [[SPARQL11-OVERVIEW]].
Developers who
require any of the facilities listed above or need to serialize an <a>RDF graph</a>
or <a>Dataset</a> in a JSON-based syntax will find JSON-LD of interest. People
intending to use JSON-LD with RDF tools will find it can be used as another
RDF syntax, as with [[Turtle]] and [[TriG]]. Complete details of how JSON-LD relates
to RDF are in section <a href="#relationship-to-rdf"></a>.
</p>
<p>The syntax is designed to not disturb already
deployed systems running on JSON, but provide a smooth upgrade path from
JSON to JSON-LD. Since the shape of such data varies wildly, JSON-LD
features mechanisms to reshape documents into a deterministic structure
which simplifies their processing.</p>
<section class="informative">
<h2>How to Read this Document</h2>
<p>This document is a detailed specification for a serialization of Linked
Data in JSON. The document is primarily intended for the following audiences:</p>
<ul>
<li>Software developers who want to encode Linked Data in a variety of
programming languages that can use JSON</li>
<li>Software developers who want to convert existing JSON to JSON-LD</li>
<li>Software developers who want to understand the design decisions and
language syntax for JSON-LD</li>
<li>Software developers who want to implement processors and APIs for
JSON-LD</li>
<li>Software developers who want to generate or consume Linked Data,
an <a>RDF graph</a>, or an <a>RDF Dataset</a> in a JSON syntax</li>
</ul>
<p>A companion document, the JSON-LD 1.1 Processing Algorithms and API specification
[[JSON-LD11-API]], specifies how to work with JSON-LD at a higher level by
providing a standard library interface for common JSON-LD operations.</p>
<p>To understand the basics in this specification you must first be familiar with
<a data-cite="RFC8259" data-no-xref="">JSON</a>, which is detailed in [[RFC8259]].</p>
<p>This document almost exclusively uses the term IRI
(<a data-cite="ld-glossary#internationalized-resource-identifier">Internationalized Resource Indicator</a>)
when discussing hyperlinks. Many Web developers are more familiar with the
URL (<a data-cite="ld-glossary#uniform-resource-locator">Uniform Resource Locator</a>)
terminology. The document also uses, albeit rarely, the URI
(<a data-cite="ld-glossary#uniform-resource-identifier">Uniform Resource Indicator</a>)
terminology. While these terms are often used interchangeably among
technical communities, they do have important distinctions from one
another and the specification goes to great lengths to try and use the
proper terminology at all times.</p>
<p>This document can highlight changes since the [[[JSON-LD10]]] version.
Select to <button class="show-changes"></button> changes.</p>
</section>
<section class="informative">
<h2>Contributing</h2>
<p>There are a number of ways that one may participate in the development of
this specification:</p>
<ul>
<li>Technical discussion typically occurs on the working group mailing list:
<a href="https://lists.w3.org/Archives/Public/public-json-ld-wg/">public-json-ld-wg@w3.org</a></li>
<li>The working group uses <a href="https://irc.w3.org/?channels=json-ld">#json-ld</a>
IRC channel is available for real-time discussion on <a href="https://irc.w3.org">irc.w3.org</a>.</li>
<li>The <a href="https://webchat.freenode.net/?channels=json-ld">#json-ld</a>
IRC channel is also available for real-time discussion on irc.freenode.net.</li>
</ul>
</section>
<section class="informative">
<h2>Typographical conventions</h2>
<div data-include="common/typographical-conventions.html"></div>
</section>
<section class="informative">
<h2>Terminology</h2>
<p>This document uses the following terms as defined in external specifications
and defines terms specific to JSON-LD.</p>
<div data-include="common/terms.html"></div>
</section>
<section class="informative">
<h2>Design Goals and Rationale</h2>
<p>JSON-LD satisfies the following design goals:</p>
<dl>
<dt>Simplicity</dt>
<dd>No extra processors or software libraries are necessary to use JSON-LD
in its most basic form. The language provides developers with a very easy
learning curve. Developers not concerned with Linked Data only need to understand JSON,
and know to include but ignore the <code>@context</code> property,
to use the basic functionality in JSON-LD.</dd>
<dt>Compatibility</dt>
<dd>A JSON-LD document is always a valid JSON document. This ensures that
all of the standard JSON libraries work seamlessly with JSON-LD documents.</dd>
<dt>Expressiveness</dt>
<dd>The syntax serializes labeled directed graphs. This ensures that almost
every real world data model can be expressed.</dd>
<dt>Terseness</dt>
<dd>The JSON-LD syntax is very terse and human readable, requiring as
little effort as possible from the developer.</dd>
<dt>Zero Edits, most of the time</dt>
<dd>JSON-LD ensures a smooth and simple transition from existing
JSON-based systems. In many cases,
zero edits to the JSON document and the addition of one line to the HTTP response
should suffice (see <a class="sectionRef" href="#interpreting-json-as-json-ld"></a>).
This allows organizations that have
already deployed large JSON-based infrastructure to use JSON-LD's features
in a way that is not disruptive to their day-to-day operations and is
transparent to their current customers. However, there are times where
mapping JSON to a graph representation is a complex undertaking.
In these instances, rather than extending JSON-LD to support
esoteric use cases, we chose not to support the use case. While Zero
Edits is a design goal, it is not always possible without adding
great complexity to the language. JSON-LD focuses on simplicity when
possible.</dd>
<dt>Usable as RDF</dt>
<dd>JSON-LD is usable by developers as
idiomatic JSON, with no need to understand RDF [[RDF11-CONCEPTS]].
JSON-LD is also usable as RDF, so people intending to use JSON-LD
with RDF tools will find it can be used like any other RDF syntax.
Complete details of how JSON-LD relates to RDF are in section
<a href="#relationship-to-rdf"></a>.</dd>
</dl>
</section>
<section class="informative">
<h2>Data Model Overview</h2>
<p>Generally speaking, the data model described by a <a>JSON-LD document</a> is a labeled, directed <a>graph</a>.
The graph contains <a>nodes</a>, which are connected by directed-arcs.
A node is either a <a>resource</a> with <a>properties</a>, or the data values of those properties including
<a>strings</a>, <a>numbers</a>, <a>typed values</a> (like dates and times) and <a>IRIs</a>.</p>
<p class="changed">Within a directed graph, nodes are <a>resources</a>, and may
be <em>unnamed</em>, i.e., not identified by an <a>IRI</a>;
which are called <a>blank nodes</a>,
and may be identified using a <a>blank node identifier</a>.
These identifiers may be required to represent a fully connected graph
using a tree structure, such as JSON, but otherwise have no
intrinsic meaning.
Literal values, such as <a>strings</a> and <a>numbers</a>, are also considered <a>resources</a>,
and JSON-LD distinguishes between <a>node objects</a> and <a>value objects</a> to distinguish between the different
kinds of <a>resources</a>.</p>
<p>This simple data model is incredibly
flexible and powerful, capable of modeling almost any kind of
data. For a deeper explanation of the data model, see
section <a href="#data-model"></a>.</p>
<p>Developers who are familiar with Linked Data technologies will
recognize the data model as the RDF Data Model. To dive deeper into how
JSON-LD and RDF are related, see
section <a href="#relationship-to-rdf"></a>.</p>
<p>At the surface level, a <a>JSON-LD document</a> is simply
<a data-cite="RFC8259" data-no-xref="">JSON</a>, detailed in [[RFC8259]].
For the purpose of describing the core data structures,
this is limited to <a>arrays</a>, <a>maps</a> (the parsed version of a <a>JSON Object</a>),
<a>strings</a>, <a>numbers</a>, <a>booleans</a>, and <a>null</a>,
<span class="changed">called the <a>JSON-LD internal representation</a>.
This allows surface syntaxes other than JSON
to be manipulated using the same algorithms, when the syntax maps
to equivalent core data structures</span>.</p>
<p class="changed note">Although not discussed in this specification,
parallel work using [[[YAML]]] [[YAML]]
and binary representations such as [[[RFC7049]]] [[RFC7049]]
could be used to map into the <a>internal representation</a>, allowing
the JSON-LD 1.1 API [[JSON-LD11-API]] to operate as if the source was a
JSON document.</p>
</section>
<section class="informative">
<h2>Syntax Tokens and Keywords</h2>
<p>JSON-LD specifies a number of syntax tokens and <a>keywords</a>
that are a core part of the language.
A normative description of the <a>keywords</a> is given in <a class="sectionRef" href="#keywords"></a>.
</p>
<dl data-sort>
<dt><code>@context</code></dt>
<dd>Used to define the short-hand names that are used throughout a JSON-LD
document. These short-hand names are called <a>terms</a> and help
developers to express specific identifiers in a compact manner. The
<code>@context</code> keyword is described in detail in
<a class="sectionRef" href="#the-context"></a>.</dd>
<dt class="changed"><code>@direction</code></dt>
<dd class="changed">Used to set the <a>base direction</a> of a <a>JSON-LD value</a>,
which are not <a>typed values</a> (e.g. <a>strings</a>, or <a>language-tagged strings</a>).
This keyword is described in
<a class="sectionRef" href="#string-internationalization"></a>.</dd>
<dt><code>@id</code></dt>
<dd>Used to uniquely identify <a>node objects</a> that are being described in the document
with <a>IRIs</a> or
<a>blank node identifiers</a>. This keyword
is described in <a class="sectionRef" href="#node-identifiers"></a>.
A <a>node reference</a> is a <a>node object</a> containing only the `@id` property,
which may represent a reference to a <a>node object</a> found elsewhere in the document.</dd>
<dt><code>@value</code></dt>
<dd>Used to specify the data that is associated with a particular
<a>property</a> in the graph. This keyword is described in
<a class="sectionRef" href="#string-internationalization"></a> and
<a class="sectionRef" href="#typed-values"></a>.</dd>
<dt><code>@language</code></dt>
<dd>Used to specify the language for a particular string value or the default
language of a JSON-LD document. This keyword is described in
<a class="sectionRef" href="#string-internationalization"></a>.</dd>
<dt><code>@type</code></dt>
<dd>Used to set the type of a <a>node</a> or the datatype of a <a>typed value</a>.
This keyword is described further in <a class="sectionRef" href="#specifying-the-type"></a>
and <a class="sectionRef" href="#typed-values"></a>.
<div class="note">The use of <code>@type</code> to define a type for both
<a>node objects</a> and <a>value objects</a> addresses the basic need to type data,
be it a literal value or a more complicated resource.
Experts may find the overloaded use of the <code>@type</code> keyword for both purposes concerning,
but should note that Web developer usage of this feature over multiple years
has not resulted in its misuse due to the far less frequent use of <code>@type</code>
to express typed literal values.
</div>
</dd>
<dt><code>@container</code></dt>
<dd>Used to set the default container type for a <a>term</a>.
This keyword is described in the following sections:
<ul>
<li><a class="sectionRef" href="#sets-and-lists"></a>,</li>
<li><a class="sectionRef" href="#data-indexing"></a>,</li>
<li><a class="sectionRef" href="#language-indexing"></a>,</li>
<li class="changed"><a class="sectionRef" href="#node-identifier-indexing"></a>,</li>
<li class="changed"><a class="sectionRef" href="#node-type-indexing"></a></li>
<li class="changed"><a class="sectionRef" href="#named-graphs"></a>,</li>
<li class="changed"><a class="sectionRef" href="#named-graph-indexing"></a>, and</li>
<li class="changed"><a class="sectionRef" href="#named-graph-data-indexing"></a></li>
</ul></dd>
<dt><code>@list</code></dt>
<dd>Used to express an ordered set of data.
This keyword is described in <a class="sectionRef" href="#lists"></a>.</dd>
<dt><code>@set</code></dt>
<dd>Used to express an unordered set of data and to ensure that values are always
represented as arrays. This keyword is described in
<a class="sectionRef" href="#sets"></a>.</dd>
<dt><code>@reverse</code></dt>
<dd>Used to express reverse properties. This keyword is described in
<a class="sectionRef" href="#reverse-properties"></a>.</dd>
<dt><code>@index</code></dt>
<dd>Used to specify that a container is used to index information and
that processing should continue deeper into a JSON data structure.
This keyword is described in <a class="sectionRef" href="#data-indexing"></a>.</dd>
<dt><code>@base</code></dt>
<dd>Used to set the <a>base IRI</a> against which to resolve those <a>relative IRI references</a>
which are otherwise interpreted relative to the document.
This keyword is described in <a class="sectionRef" href="#base-iri"></a>.</dd>
<dt><code>@vocab</code></dt>
<dd>Used to expand properties and values in <code>@type</code> with a common prefix
<a>IRI</a>. This keyword is described in <a class="sectionRef" href="#default-vocabulary"></a>.</dd>
<dt><code>@graph</code></dt><dd>Used to express a <a>graph</a>.
This keyword is described in <a class="sectionRef" href="#named-graphs"></a>.</dd>
<dt class="changed"><code>@nest</code></dt><dd class="changed">Used to define a <a>property</a> of a <a>node object</a> that groups together properties of that node, but is not an edge in the graph.</dd>
<dt class="changed"><code>@none</code></dt><dd class="changed">Used as an index value
in an <a>index map</a>, <a>id map</a>, <a>language map</a>, <a>type map</a>, or elsewhere where a <a>map</a> is
used to index into other values, when the indexed node does not have the feature being indexed.</dd>
<dt class="changed"><code>@prefix</code></dt><dd class="changed">
With the value <code>true</code>, allows this <a>term</a> to be used to construct a <a>compact IRI</a>
when compacting.
With the value `false` prevents the term from being used to construct a <a>compact IRI</a>.
Also determines if the term will be considered when expanding <a>compact IRIs</a>.</dd>
<dt class="changed"><code>@version</code></dt><dd class="changed">
Used in a <a>context definition</a> to set the <a>processing mode</a>.
New features since [[[JSON-LD10]]] [[JSON-LD10]] described in this specification are
not available when <a>processing mode</a> has been explicitly set to
`json-ld-1.0`.
<div class="note">Within a <a>context definition</a> `@version` takes the specific value `1.1`, not
`"json-ld-1.1"`, as a JSON-LD 1.0 processor may accept a string value for `@version`,
but will reject a numeric value.</div>
<div class="note">The use of `1.1` for the value of `@version` is intended to
cause a JSON-LD 1.0 processor to stop processing.
Although it is clearly meant to be related to JSON-LD 1.1, it does not
otherwise adhere to the requirements for <a href="https://semver.org/">Semantic Versioning</a>.</div>
</dd>
<dt class="changed"><code>@json</code></dt><dd class="changed">
Used as the <code>@type</code> value of a <a>JSON literal</a>.
This keyword is described in <a href="#json-literals" class="sectionRef"></a>.
</dd>
<dt class="changed"><code>:</code></dt><dd class="changed">
The separator for JSON keys and values that use <a>compact IRIs</a>.</dd>
<dt class="changed">`@propagate`</dt><dd class="changed">
Used in a <a>context definition</a> to change the scope of that context.
By default, it is `true`,
meaning that contexts propagate across <a>node objects</a>
(other than for <a>type-scoped contexts</a>, which default to `false`).
Setting this to `false` causes term definitions created within that context
to be removed when entering a new <a>node object</a>.</dd>
<dt class="changed">`@protected`</dt><dd class="changed">
Used to prevent <a>term definitions</a> of a context to be overridden by other contexts.
This keyword is described in <a class="sectionRef" href="#protected-term-definitions"></a>.
<dt class="changed">`@import`</dt><dd class="changed">
Used in a <a>context definition</a> to load an external context
within which the containing <a>context definition</a> is merged.
This can be useful to add JSON-LD 1.1 features to JSON-LD 1.0 contexts.</dd>
<dt class="changed">`@included`</dt><dd class="changed">
Used in a top-level <a>node object</a> to define an <a>included block</a>,
for including secondary <a>node objects</a> within another <a>node object</a>.
</dd>
</dl>
<p>All keys, <a>keywords</a>, and values in JSON-LD are case-sensitive.</p>
</section>
</section>
<section id="conformance">
<p>A <a>JSON-LD document</a> complies with this specification if it follows
the normative statements in appendix <a href="#json-ld-grammar"></a>. JSON documents
can be interpreted as JSON-LD by following the normative statements in
<a class="sectionRef" href="#interpreting-json-as-json-ld"></a>. For convenience, normative
statements for documents are often phrased as statements on the properties of the document.</p>
<p>This specification makes use of the following namespace prefixes:</p>
<table class="simple">
<thead><tr>
<th>Prefix</th>
<th>IRI</th>
</tr></thead>
<tbody>
<tr>
<td>dc11</td>
<td>http://purl.org/dc/elements/1.1/</td>
</tr>
<tr>
<td>dcterms</td>
<td>http://purl.org/dc/terms/</td>
</tr>
<tr>
<td>cred</td>
<td>https://w3id.org/credentials#</td>
</tr>
<tr>
<td>foaf</td>
<td>http://xmlns.com/foaf/0.1/</td>
</tr>
<tr>
<td>geojson</td>
<td>https://purl.org/geojson/vocab#</td>
</tr>
<tr>
<td>prov</td>
<td>http://www.w3.org/ns/prov#</td>
</tr>
<tr>
<td>i18n</td>
<td>https://www.w3.org/ns/i18n#</td>
</tr>
<tr>
<td>rdf</td>
<td>http://www.w3.org/1999/02/22-rdf-syntax-ns#</td>
</tr>
<tr>
<td>schema</td>
<td>http://schema.org/</td>
</tr>
<tr>
<td>skos</td>
<td>http://www.w3.org/2004/02/skos/core#</td>
</tr>
<tr>
<td>xsd</td>
<td>http://www.w3.org/2001/XMLSchema#</td>
</tr>
</tbody>
</table>
<p>These are used within this document as part of a <a>compact IRI</a>
as a shorthand for the resulting <a>IRI</a>, such as <code>dcterms:title</code>
used to represent <code>http://purl.org/dc/terms/title</code>.</p>
</section>
<section class="informative">
<h1>Basic Concepts</h1>
<p>JSON [[RFC8259]] is a lightweight, language-independent data interchange format.
It is easy to parse and easy to generate. However, it is difficult to integrate JSON
from different sources as the data may contain keys that conflict with other
data sources. Furthermore, JSON has no
built-in support for hyperlinks, which are a fundamental building block on
the Web. Let's start by looking at an example that we will be using for the
rest of this section:</p>
<pre class="example" data-transform="updateExample"
title="Sample JSON document">
<!--
{
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"image": "http://manu.sporny.org/images/manu.png"
}
-->
</pre>
<p>It's obvious to humans that the data is about a person whose
<code>name</code> is "Manu Sporny"
and that the <code>homepage</code> property contains the URL of that person's homepage.
A machine doesn't have such an intuitive understanding and sometimes,
even for humans, it is difficult to resolve ambiguities in such representations. This problem
can be solved by using unambiguous identifiers to denote the different concepts instead of
tokens such as "name", "homepage", etc.</p>
<p>Linked Data, and the Web in general, uses <a>IRIs</a>
(<a data-cite="RFC3987#section-2">Internationalized Resource Identifiers</a> as described in [[RFC3987]]) for unambiguous
identification. The idea is to use <a>IRIs</a>
to assign unambiguous identifiers to data that may be of use to other developers.
It is useful for <a>terms</a>,
like <code>name</code> and <code>homepage</code>, to expand to <a>IRIs</a>
so that developers don't accidentally step on each other's terms. Furthermore, developers and
machines are able to use this <a>IRI</a> (by using a web browser, for instance) to go to
the term and get a definition of what the term means. This process is known as <a>IRI</a>
dereferencing.</p>
<p>Leveraging the popular <a href="http://schema.org/">schema.org vocabulary</a>,
the example above could be unambiguously expressed as follows:</p>
<aside class="example ds-selector-tabs"
title="Sample JSON-LD document using full IRIs instead of terms">
<div class="selectors">
<button class="selected" data-selects="expanded">Expanded (Input)</button>
<button data-selects="statements">Statements</button>
<button data-selects="turtle">Turtle (Result)</button>
<a class="playground" target="_blank" href="">PG</a>
</div>
<pre class="expanded input selected nohighlight" data-transform="updateExample">
<!--
{
"****http://schema.org/name****": "Manu Sporny",
"****http://schema.org/url****": ****{
"@id": ****"http://manu.sporny.org/"
####↑ The '@id' keyword means 'This value is an identifier that is an IRI'####
****}****,
"****http://schema.org/image****": ****{
"@id": ****"http://manu.sporny.org/images/manu.png"
****}****
}
-->
</pre>
<table class="statements"
data-result-for="Sample JSON-LD document using full IRIs instead of terms-expanded"
data-to-rdf>
<thead><tr><th>Subject</th><th>Property</th><th>Value</th></tr></thead>
<tbody>
<tr><td>_:b0</td><td>schema:image</td><td>http://manu.sporny.org/images/manu.png</td></tr>
<tr><td>_:b0</td><td>schema:name</td><td>Manu Sporny</td></tr>
<tr><td>_:b0</td><td>schema:url</td><td>http://manu.sporny.org/</td></tr>
</tbody>
</table>
<pre class="turtle"
data-content-type="text/turtle"
data-result-for="Sample JSON-LD document using full IRIs instead of terms-expanded"
data-transform="updateExample"
data-to-rdf>
<!--
@prefix schema: <http://schema.org/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
[
schema:image <http://manu.sporny.org/images/manu.png>;
schema:name "Manu Sporny";
schema:url <http://manu.sporny.org/>
] .
-->
</pre>
</aside>
<p>In the example above, every property is unambiguously identified by an <a>IRI</a> and all values
representing <a>IRIs</a> are explicitly marked as such by the
<code>@id</code> <a>keyword</a>. While this is a valid JSON-LD
document that is very specific about its data, the document is also overly verbose and difficult
to work with for human developers. To address this issue, JSON-LD introduces the notion
of a <a>context</a> as described in the next section.</p>
<p>This section only covers the most basic features of JSON-LD. More advanced features,
including <a>typed values</a>, <a href="#indexed-values">indexed values</a>, and <a>named graphs</a>,
can be found in <a class="sectionRef" href="#advanced-concepts"></a>.</p>
<section class="informative">
<h2>The Context</h2>
<p>When two people communicate with one another, the conversation takes
place in a shared environment, typically called
"the context of the conversation". This shared context allows the
individuals to use shortcut terms, like the first name of a mutual friend,
to communicate more quickly but without losing accuracy. A context in
JSON-LD works in the same way. It allows two applications to use shortcut
terms to communicate with one another more efficiently, but without
losing accuracy.</p>
<p>Simply speaking, a <a>context</a> is used to map <a>terms</a> to <a>IRIs</a>.
<a>Terms</a> are case sensitive and most valid <a>strings</a> that are not reserved JSON-LD <a>keywords</a>
can be used as a <a>term</a>.
<span class="changed">Exceptions are the empty string `""` and strings that have the form
of a keyword (i.e., starting with `"@"` followed exclusively by one or more <em>ALPHA</em> characters (see [[RFC5234]])), which must not be used as terms.
Strings that have the form of
an <a>IRI</a> (e.g., containing a `":"`) should not be used as terms.</span></p>
<p>For the sample document in the previous section, a <a>context</a> would
look something like this:</p>
<pre class="example context nohighlight" data-transform="updateExample"
data-context-for="Sample JSON document"
title="Context for the sample document in the previous section">
<!--
{
****"@context": {
"name": "http://schema.org/name",****
####↑ This means that 'name' is shorthand for 'http://schema.org/name'####
****"image": {
"@id": "http://schema.org/image",****
####↑ This means that 'image' is shorthand for 'http://schema.org/image'####
****"@type": "@id"****
####↑ This means that a string value associated with 'image'
should be interpreted as an identifier that is an IRI####
****},
"homepage": {
"@id": "http://schema.org/url",****
####↑ This means that 'homepage' is shorthand for 'http://schema.org/url'####
****"@type": "@id"****
####↑ This means that a string value associated with 'homepage'
should be interpreted as an identifier that is an IRI#### ****
}
}****
}
-->
</pre>
<p>As the <a>context</a> above shows, the value of a <a>term definition</a> can
either be a simple string, mapping the <a>term</a> to an <a>IRI</a>,
or a <a>map</a>.</p>
<p>A <a>context</a> is introduced using an <a>entry</a> with the key <code>@context</code> and may
appear within a <a>node object</a> or a <a>value object</a>.</p>
<p>When an <a>entry</a> with a <a>term</a> key has a <a>map</a> value, the <a>map</a> is called
an <a>expanded term definition</a>. The example above specifies that
the values of <code>image</code> and <code>homepage</code>, if they are
strings, are to be interpreted as
<a>IRIs</a>. <a>Expanded term definitions</a>
also allow terms to be used for <a href="#data-indexing">index maps</a>
and to specify whether <a>array</a> values are to be
interpreted as <a href="#sets">sets</a> or <a href="#lists">lists</a>.
<a>Expanded term definitions</a> may
be defined using <a>IRIs</a> or
<a>compact IRIs</a> as keys, which is
mainly used to associate type or language information with an
<a>IRIs</a> or <a>compact IRI</a>.</p>
<p><a>Contexts</a> can either be directly embedded
into the document (an <a>embedded context</a>) or be referenced using a URL.
Assuming the context document in the previous
example can be retrieved at <code>https://json-ld.org/contexts/person.jsonld</code>,
it can be referenced by adding a single line and allows a JSON-LD document to
be expressed much more concisely as shown in the example below:</p>
<aside class="example ds-selector-tabs"
title="Referencing a JSON-LD context">
<div class="selectors">
<button class="selected input" data-selects="compacted">Compacted (Input)</button>
<button data-selects="expanded">Expanded (Result)</button>
<button data-selects="statements">Statements</button>
<button data-selects="turtle">Turtle</button>
<a class="playground" target="_blank" href="">PG</a>
</div>
<pre class="compacted input selected nohighlight" data-transform="updateExample">
<!--
{
****"@context": "https://json-ld.org/contexts/person.jsonld",****
"name": "Manu Sporny",
"homepage": "http://manu.sporny.org/",
"image": "http://manu.sporny.org/images/manu.png"
}
-->
</pre>
<pre class="expanded result nohighlight"
data-transform="updateExample"
data-result-for="Referencing a JSON-LD context-compacted">
<!--
[{
"http://xmlns.com/foaf/0.1/name": [{"@value": "Manu Sporny"}],
"http://xmlns.com/foaf/0.1/homepage": [{ "@id": "http://manu.sporny.org/" }],
"http://xmlns.com/foaf/0.1/img": [{ "@id": "http://manu.sporny.org/images/manu.png" }]
}]
-->
</pre>
<table class="statements"
data-result-for="Referencing a JSON-LD context-expanded"
data-to-rdf>
<thead><tr><th>Subject</th><th>Property</th><th>Value</th></tr></thead>
<tbody>
<tr><td>_:b0</td><td>foaf:name</td><td>Manu Sporny</td></tr>
<tr><td>_:b0</td><td>foaf:homepage</td><td>http://manu.sporny.org/</td></tr>
<tr><td>_:b0</td><td>foaf:img</td><td>http://manu.sporny.org/images/manu.png</td></tr>
</tbody>
</table>
<pre class="turtle"
data-content-type="text/turtle"
data-result-for="Referencing a JSON-LD context-expanded"
data-transform="updateExample"
data-to-rdf>
<!--
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
[
foaf:name "Manu Sporny";
foaf:homepage <http://manu.sporny.org/>;
foaf:img <http://manu.sporny.org/images/manu.png>
] .
-->
</pre>
</aside>
<p>The referenced context not only specifies how the terms map to
<a>IRIs</a> in the Schema.org vocabulary but also
specifies that string values associated with
the <code>homepage</code> and <code>image</code> property
can be interpreted as an <a>IRI</a> (<code>"@type": "@id"</code>,
see <a class="sectionRef" href="#iris"></a> for more details). This information allows developers
to re-use each other's data without having to agree to how their data will interoperate
on a site-by-site basis. External JSON-LD context documents may contain extra
information located outside of the <code>@context</code> key, such as
documentation about the <a>terms</a> declared in the
document. Information contained outside of the <code>@context</code> value
is ignored when the document is used as an external <dfn data-lt="context document">JSON-LD context document</dfn>.</p>
<p class="changed">A remote context may also be referenced using a relative URL,
which is resolved relative to the location of the document containing the reference.
For example, if a document were located at <code>http://example.org/document.jsonld</code>
and contained a relative reference to <code>context.jsonld</code>,
the referenced context document would be found relative at <code>http://example.org/context.jsonld</code>.</p>
<pre class="example nohighlight changed"
title="Loading a relative context"