Microdata (HTML): Difference between revisions

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{{short description|Specification for metadata in web pages}}

'''Microdata''' is a proposed feature of [[HTML5]] intended to provide a simple way to embed [[semantic markup]] into [[HTML]] documents.

{{Other uses|Microdata (disambiguation)}}

{{HTML}}

'''Microdata''' is a [[WHATWG]] [[HTML]] specification used to nest [[metadata]] within existing content on web pages.<ref name="WHATWG"/> [[Search engines]], [[web crawlers]], and [[Web browser|browsers]] can extract and process Microdata from a web page and use it to provide a richer browsing experience for users. Search engines benefit greatly from direct access to Microdata because it allows them to understand the information on web pages and provide more relevant [[Search engine results page|results]] to users.<ref>{{cite web|url=http://www.lyquix.com/blog-and-news/microdata-the-future-of-search-engine-relevance-and-search-engine-optimization-seo |title=MicroData - The Future of Search Engine Relevance and Optimization (SEO) |publisher=Lyquix.com |access-date=2016-06-30}}</ref><ref>Schema.org http://schema.org/</ref> Microdata uses a supporting vocabulary to describe an item and name-value pairs to assign values to its properties.<ref name="DIVE"/> Microdata is an attempt to provide a simpler way of annotating [[HTML element]]s with machine-readable tags than the similar approaches of using [[RDFa]] and [[microformat]]s.

In 2013, because the W3C HTML Working Group failed to find someone to serve as an editor for the '''Microdata HTML''' specification, its development was terminated with a 'Note'.<ref>{{cite mailing list|url=https://lists.w3.org/Archives/Public/public-html-admin/2013Oct/0018.html |title=WG Decision to publish HTML Microdata as a WG Note |mailing-list=[e-mail] |date=2 Oct 2013 |first=Paul |last=Cotton |access-date=2016-06-30}}</ref><ref>{{cite web|url=http://www.w3.org/TR/microdata/ |title=HTML Microdata |publisher=W3.org |date=23 June 2014 |access-date=2016-06-30}}</ref> However, since that time, two new editors were selected, and five newer versions of the working draft have been published,<ref>{{Cite web|url=https://www.w3.org/TR/2017/WD-microdata-20170504/|title=HTML Microdata W3C First Public Working Draft 04 May 2017|website=World Wide Web Consortium (W3C)|access-date=2017-09-06}}</ref><ref>{{Cite web|url=https://www.w3.org/TR/2017/WD-microdata-20170626/|title=HTML Microdata W3C Working Draft 26 June 2017|website=World Wide Web Consortium (W3C)|access-date=2017-09-06}}</ref><ref>{{Cite web|url=https://www.w3.org/TR/2017/WD-microdata-20171009/|title=HTML Microdata W3C Working Draft 09 October 2017|date=9 October 2017|website=World Wide Web Consortium (W3C)|access-date=16 March 2018}}</ref><ref name=":0">{{Cite web|url=https://www.w3.org/TR/2017/WD-microdata-20171010/|title=HTML Microdata W3C Working Draft 10 October 2017|date=10 October 2017|website=World Wide Web Consortium (W3C)|access-date=16 March 2018}}</ref> the most recent being Working Draft 26 April 2018.<ref name=":0" />

Microdata can be viewed as an extension of the existing [[microformat]] idea which attempts to address the deficiencies of microformats without the complexity of systems such as [[RDFa]].

== Vocabularies ==

Microdata vocabularies do not provide the [[semantics]], or meaning of an Item.<ref>{{Cite web | title = HTML Standard | url = https://html.spec.whatwg.org/multipage/microdata.html | website = Web Hypertext Application Technology Working Group | access-date = 30 December 2016}}</ref> Web developers can design a custom vocabulary or use vocabularies available on the web. A collection of commonly used markup vocabularies are provided by [[Schema.org]] schemas which include: ''Person'', "''Place''", ''Event'', ''Organization'', ''Product'', ''Review'', ''Review-aggregate'', ''Breadcrumb'', ''Offer'', ''Offer-aggregate''. The website schema.org was established by search engine operators like [[Google]], [[Microsoft]], [[Yahoo!]], and [[Yandex]], which use microdata markup to improve search results.<ref>{{cite book|title=HTML5: The missing manual|last=MacDonald|first=Matthew|edition=2nd|publisher=[[O'Reilly and Associates]]|date=2014|isbn=978-1-4493-6326-0}}</ref>{{rp|85}}

For some purposes, an ad-hoc vocabulary is adequate. For others, a vocabulary will need to be designed. Where possible, authors are encouraged to re-use existing vocabularies, as this makes content re-use easier.<ref name="WHATWG"/>

== Localization ==

In some cases, search engines covering specific regions may provide locally-specific extensions of microdata. For example, [[Yandex]], a major search engine in Russia, supports [[microformats]] such as [[hCard]] (company contact information), [[hRecipe]] (food recipe), [[hReview]] (market reviews) and [[hProduct]] (product data) and provides its own format for definition of the terms and encyclopedic articles. This extension was made in order to solve [[transliteration]] problems between the Cyrillic and Latin alphabets. After the implementation of additional parameters from Schema's vocabulary,<ref name="AcademicYan"/> indexation of information in Russian-language web-pages became more successful.

== Global attributes ==

* <code>itemscope</code> – Creates the Item and indicates that descendants of this [[HTML element|element]] contain information about it.<ref name="WHATWG"/>

* <code>itemtype</code> – A valid URL of a vocabulary that describes the item and its properties' context.

* <code>itemid</code> – Indicates a unique identifier of the item.

* <code>itemprop</code> – Indicates that its containing tag holds the value of the specified item property. The property's name and value context are described by the item's vocabulary. Properties values usually consist of string values, but can also use URLs using the <code>a</code> element and its <code>href</code> attribute, the <code>img</code> element and its <code>src</code> attribute, or other elements that link to or embed external resources.<ref name=WHATWG/>

* <code>itemref</code> – Properties that are not descendants of the element with the <code>itemscope</code> attribute can be associated with the item using this attribute. Provides a list of element IDs (not <code>itemid</code>s) with additional properties elsewhere in the document.<ref name="WHATWG"/>

* <code>datetime</code> – Indicates date or duration as specified by [[ISO 8601]] standard.

== Example ==

The following HTML5 markup may be found on a typical “About” page containing information about a person:

<syntaxhighlight lang="html">

<div> Hello, my name is John Doe, I am a graduate research assistant at

the University of Dreams.

My friends call me Johnny.

You can visit my homepage at <a href="http://www.example.com/~JohnnyD">www.example.com/~JohnnyD</a>.

I live at 1234 Peach Drive, Warner Robins, Georgia.</div>

</syntaxhighlight>

Here is the same markup with added [[Schema.org]]<ref>{{cite web|url=http://schema.org/docs/documents.html |title=Documentation |publisher=Schema.org |access-date=2016-06-30}}</ref><ref>{{cite web|url=http://schema.org/docs/full.html |title=Type Hierarchy |publisher=Schema.org |access-date=2016-06-30}}</ref><ref>{{Cite web |url=http://schema.rdfs.org/all.ttl |title=Schema.org Turtle RDFS Schema |access-date=2013-05-29 |archive-url=https://web.archive.org/web/20140921103224/http://schema.rdfs.org/all.ttl |archive-date=2014-09-21 |url-status=dead }}</ref> Microdata:

<syntaxhighlight lang="html">

<div itemscope itemtype="http://schema.org/Person">

Hello, my name is

<span itemprop="name">John Doe</span>,

I am a

<span itemprop="jobTitle">graduate research assistant</span>

at the

<span itemprop="affiliation">University of Dreams</span>.

My friends call me

<span itemprop="additionalName">Johnny</span>.

You can visit my homepage at

<a href="http://www.example.com/~JohnnyD" itemprop="url">www.example.com/~JohnnyD</a>.

<div itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">

I live at

<span itemprop="streetAddress">1234 Peach Drive</span>,

<span itemprop="addressLocality">Warner Robins</span>,

<span itemprop="addressRegion">Georgia</span>.

</div>

</div>

</syntaxhighlight>

As the above example shows, Microdata items can be nested. In this case, an item of type http://schema.org/PostalAddress is nested inside an item of type http://schema.org/Person.

The following text shows how Google parses the Microdata from the above example code. Developers can test pages containing Microdata using Google's ''Rich Snippet Testing Tool''.<ref name="GoogleRS"/>

<div class="plainlinks">

Item

Type: http://schema.org/Person

name = John Doe

jobTitle = graduate research assistant

affiliation = University of Dreams

additionalName = Johnny

url = <nowiki>http://www.example.com/~JohnnyD</nowiki>

address = Item(1)

Item 1

Type: http://schema.org/PostalAddress

streetAddress = 1234 Peach Drive

addressLocality = Warner Robins

addressRegion = Georgia

</div>

The same machine-readable terms can be used not only in HTML Microdata, but also in other annotations such as [[RDFa]] or [[JSON-LD]] in the markup, or in an external [[Resource Description Framework|RDF]] file in a serialization such as [[RDF/XML]], [[Notation3]], or [[Turtle (syntax)|Turtle]].

== Support ==

* Servers: [[Google]] can<ref name=GoogleCan /> use microdata in its [[Search engine results page|result pages]].<ref name=GoogleRS /> It was the preferred snippet format for the [[Google+]] social network.<ref>{{cite AV media|url=https://www.youtube.com/watch?v=4W8Ah394bH8 |archive-url=https://ghostarchive.org/varchive/youtube/20211215/4W8Ah394bH8 |archive-date=2021-12-15 |url-status=live|title=Types of Rich Snippets |author=Google Webmasters Channel |medium=Video |date=2011-12-06 |access-date=2016-06-30}}{{cbignore}}</ref>

* Browsers: {{As of|2021|7}}, no major browser supports the Microdata [[Document Object Model|DOM]] [[API]].<ref>{{Cite web|title=Microdata DOM API - Web APIs {{!}} MDN|url=https://developer.mozilla.org/en-US/docs/Web/API/Microdata_DOM_API|access-date=2021-07-05|website=developer.mozilla.org|language=en-US}}</ref> Opera supported it from 11.60 (released in 2011), but since removed its implementation.<ref>{{cite web |author=Opera Software Documentation Team |url=http://www.opera.com/docs/changelogs/windows/1160/ |title=Opera 11.60 for Windows changelog |publisher=Opera.com |date=2011-12-06 |access-date=2016-06-30 |archive-url=https://web.archive.org/web/20141023082043/http://www.opera.com/docs/changelogs/windows/1160/ |archive-date=2014-10-23 |url-status=dead }}</ref> Firefox removed it in version 49.<ref>{{Cite web|title=909633 - Remove HTML Microdata API|url=https://bugzilla.mozilla.org/show_bug.cgi?id=909633|access-date=2021-07-05|website=bugzilla.mozilla.org|language=en}}</ref>

== See also ==

* [[Semantic web]]

* [[Microformat]]

* [[RDFa Lite]]

* [[JSON-LD]]

* [[CP/LD|CP/LD (Content Profile/Linked Document)]]

* [[Semantic HTML]]

* [[Semantic social network]]

==References==

{{Reflist|30em|refs=

<ref name="WHATWG">{{cite web|url=http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html |title=Microdata — HTML Draft Standard |publisher=Whatwg.org |access-date=2016-06-30}}</ref>

<ref name="AcademicYan">{{cite web|url=https://www.academia.edu/6732371 |title=Semantic markup deployment in Russia |publisher=Academia.edu |access-date=2016-06-30}}</ref>

<ref name="GoogleCan">{{cite web|url=https://www.google.com/support/webmasters/bin/answer.py?answer=99170 |title=Rich Snippet display clarification |date=2016-06-22 |access-date=2016-06-30}}</ref>

<ref name="GoogleRS">{{cite web|url=https://developers.google.com/structured-data/testing |title=Rich snippets (microdata, microformats, RDFa) |publisher=Google Inc. |date=2016-05-17 |access-date=2016-06-30}}</ref>

<ref name="DIVE">{{cite web|url=http://diveintohtml5.info/extensibility.html |title="Distributed," "Extensibility," And Other Fancy Words |publisher=Diveintohtml5.info |access-date=2016-06-30}}</ref>}}

== External links ==

* {{citation |url=httphttps://wwwhtml.spec.whatwg.org/specs/web-apps/current-work/multipage/linksmicrodata.html#microdata |title=Microdata &mdash; HTML5HTML Draft Standard |publisher=[[Web Hypertext Application Technology Working Group|WHATWG]]}}

* {{citation |url=httphttps://ajaxianwww.comw3.org/archivesTR/hixie-discusses-the-addition-of-html5-microdata /|title=HixieW3C discussesHTML theMicrodata additionWorking ofGroup HTML5 “microdata” |date=2009-05-11 |first=Dion |last=AlmaerNote |publisher=Ajaxian[[W3C]]}}

* {{citation |url=http://ajaxian.com/archives/hixie-discusses-the-addition-of-html5-microdata |title=Hixie discusses the addition of HTML5 "microdata" |date=2009-05-11 |first=Dion |last=Almaer |publisher=Ajaxian|archive-url=https://web.archive.org/web/20091212053447/http://ajaxian.com/archives/hixie-discusses-the-addition-of-html5-microdata |archive-date=2009-12-12 }}

* {{citation |url=http://www.data-vocabulary.org |title=HTML5 Microdata Specs |publisher=Data-Vocabulary.org}}

{{Semantic Web}}

[[Category:Microformats]]

[[Category:Semantic Web]]

[[Category:HTML]]

[[Category:Semantic HTML]]

{{web-stub}}

[[Category:Search engine optimization]]